If the Check Engine light has come on in your Lancer, Outlander, ASX, Pajero or L200, the first thing to do is read the trouble codes with a scanner and understand exactly what the engine control module is reporting. This page is a lookup table of the most common Mitsubishi trouble codes — P0011, P0101, P0171, P0300, P0420, P1603, P2100, U0101 and dozens more — covering petrol and diesel engines, the transmission, the electronic throttle, the CAN bus and the immobiliser. For each code you’ll find what it means, the models and engines it appears on most often, the typical root causes and the recommended order of diagnosis. The article is built so that, starting from the code alone, you know straight away where to look and where to begin testing — without wading through generic theory.
One thing to keep in mind: a DTC (Diagnostic Trouble Code) is only a hint about the subsystem in which the control module detected a deviation. The same code can be triggered by completely different faults — from a clogged mesh filter ahead of the OCV valve (the oil control solenoid of the variable valve timing system) to a simple oxidised ECU ground. The reverse is also true: a single physical defect (an air leak, a weak battery, a poor body ground) can throw a dozen seemingly unrelated codes at once. That’s why sound diagnosis always relies on the combination of “trouble code + system wiring diagram + Live Data parameters + ECU pinout + the car’s real-world symptoms”.
Mitsubishi has its own quirks: when decoding codes you need to account for the engine management type on petrol engines (MPI, GDI, MIVEC) and the diesel fuel system (Common Rail Denso/Bosch), as well as the destination market (JAP, EUR, GEN, USA). ECU pinouts and the operating logic of the EGR, MIVEC and throttle body can differ on the very same model between markets. This is exactly why it’s convenient to work in MotorData Automotive Electrics — for every code in the table below it has interactive colour wiring diagrams, ECU pinouts (PinData), DTC set conditions and the characteristic faults for a specific model, engine and year. In total, the MotorData database holds more than 60,000 DTC codes and dozens of Mitsubishi models from 1986 to 2023.
The table below was compiled from real-world experience diagnosing Lancer (CS, CY, CZ, Evolution), Outlander (I/II/III, PHEV), ASX, Pajero (III/IV), Pajero Sport / Montero Sport, L200 (III/IV/V), Galant, Colt, Carisma, Grandis, Eclipse Cross, Delica and other popular models. The codes are split into logical groups: intake and fuel delivery, ignition, exhaust and emissions (EGR, EVAP), electronic throttle and accelerator pedal, engine control module (PCM), the CAN data bus, transmission, Common Rail diesel engines, and the security/immobiliser systems.
There’s a lot of ground to cover, so we’ve split the material into two articles. This first article covers intake and fuel-delivery faults on petrol engines, ignition misfires, the electronic throttle and accelerator pedal, the transmission, and the engine control module. The second article will cover diesel engine codes, the exhaust system, catalytic converter and emissions (EVAP, EGR), the CAN bus and the immobiliser.
Intake and Fuel-Delivery Codes (Petrol Engines)
P0011 — MIVEC Variable Valve Timing (Bank 1) — Position Deviation
Meaning: The PCM has detected that the intake camshaft phaser isn’t reaching the commanded angle, or responds to the command too slowly. On Mitsubishi the variable valve timing system is called MIVEC (Mitsubishi Innovative Valve timing Electronic Control) and is fitted to the 4B10, 4B11, 4B12, 4J11, 4J12, 4A91, 4A92 and several other engines.
Common on: Lancer X (CY/CZ) with 4B10/4B11, Outlander II/III (4B11, 4B12), ASX (4B10/4A92), Eclipse Cross (4B40), Galant Fortis.
Possible causes:
- Low or contaminated engine oil (the most common cause — MIVEC is extremely sensitive to oil condition).
- A clogged oil passage or mesh filter ahead of the OCV solenoid.
- A faulty valve timing control valve (OCV / VVT solenoid).
- A seized or worn phaser itself.
- An open or short in the OCV control circuit.
- A stretched timing chain (relevant for 4B11/4B12 over 150,000 km).
Symptoms: rough idle (especially when warm), power loss, jerking under acceleration, increased fuel consumption, a characteristic rattle in the first seconds after a cold start. In severe cases — MIVEC failure and limp mode.
Tip for the technician: always start by checking the oil level and condition. Second step — remove the OCV valve, test it for 12 V actuation and clean it. An oil change to fresh oil of the correct viscosity (5W-30 to spec) clears P0011 in roughly half of cases. The check for the variable valve timing solenoid and its control signal is shown in the PinData section.
P0101 — Mass Air Flow Sensor (MAF) — Range/Performance
Meaning: The PCM has detected that the MAF reading is out of the allowable range — there’s a signal, but it doesn’t match the engine’s actual operating conditions (rpm, load, throttle position).
Common on: Lancer 9 (CS), Lancer X, Outlander I/II/III, ASX, Pajero III/IV, Galant.
Possible causes:
- Contamination of the MAF sensing element (an oil film from the crankcase ventilation, dust).
- An air leak downstream of the sensor (a cracked intake duct, a poorly seated clamp).
- A faulty sensor (loss of sensitivity).
- A clogged air filter.
- An open/short in the wiring or oxidised connector contacts.
Symptoms: rough idle, hesitation under acceleration, increased fuel consumption, Check Engine on. On Outlander II/III and ASX, P0101 often appears alongside P0171 (lean mixture).
Tip for the technician: before replacing the sensor, clean it with a dedicated MAF cleaner, clear the code and check whether it returns. Always check the airtightness of the duct between the MAF and the throttle, and the crankcase ventilation hoses — on 4B1x engines they get clogged with oil and “flood” the sensor.
P0105 — Manifold Absolute Pressure Sensor (MAP) — Circuit Malfunction
Meaning: The PCM isn’t receiving a correct signal from the MAP sensor. On Mitsubishi the MAP sensor is found on both petrol engines (especially turbocharged) and diesels, often together with a MAF sensor.
Common on: Lancer Evolution, Pajero Sport (4D56, 4M41), L200 (4D56, 4N15), Pajero IV (4M41 diesel), Outlander PHEV.
Possible causes:
- An open or short in the sensor signal wire.
- A faulty pressure sensor itself.
- A clogged vacuum passage to the sensor (relevant on diesels with EGR — the passage fills with soot).
- An air leak in the intake tract.
- A faulty PCM (rare).
Symptoms: hard starting, rough idle, black smoke (especially on diesels), reduced power, limp mode.
P0110 — Intake Air Temperature Sensor (IAT) — Circuit Malfunction
Meaning: The PCM has detected incorrect readings from the IAT sensor. On Mitsubishi this sensor is either built into the MAF housing or located separately in the intake manifold (turbo engines, diesels).
Possible causes:
- An open or short in the sensor circuit.
- A faulty sensor (thermistor failure).
- Oxidised connector contacts.
- A faulty MAF assembly (if the IAT is integrated).
Symptoms: increased fuel consumption, minor hesitation under acceleration, occasionally a difficult cold start. Rarely shows up at idle.
Tip for the technician: to test the temperature sensor and its circuit, use the MotorData PinData and Wiring Diagram sections for the relevant model.
P0122 / P0123 — Throttle Position Sensor (Channel 1) — Low / High Input
Meaning: The PCM has detected that the channel-1 throttle position signal is out of its operating range. Mitsubishi has used an electronic throttle body (ETV / ETCS) on virtually all models since 2003, with two independent position sensors (TPS 1 and TPS 2) for redundancy.
Common on: Lancer X, Outlander II/III, ASX, Eclipse Cross, Pajero IV, Galant USA.
Possible causes:
- A faulty throttle position sensor (TPS).
- Oxidation or a poor contact in the TPS connector.
- An open or short in the wiring between the control module and the sensor connector.
- A faulty throttle body assembly itself.
- A low +5 V reference at the control module pin (check via PinData).
Symptoms: jerking under acceleration, rpm “hanging”, limp mode (rpm and power limited), cruise control failure, Check Engine plus ASC/ASTC.
Tip for the technician: when P0122/P0123 appears together with P2100/P2101 (see below), the throttle body itself is almost always the suspect. Check the +5 V reference and sensor ground against the diagram — the problem is often right at the PCM connector.
P0130 / P0133 / P0134 — Front Oxygen Sensor Circuit (B1S1) — Malfunction / Slow Response / No Activity
Meaning: The PCM has detected a problem with the front oxygen sensor (before the catalytic converter, bank 1, sensor 1): the signal doesn’t change properly (P0134 — no activity), changes too slowly (P0133), or is out of the allowable range (P0130). Mitsubishi 4B/4J/4A engines use a conventional zirconia oxygen sensor.
Common on: Lancer 9/10, Outlander, ASX, Colt, Galant, Pajero (petrol).
Possible causes:
- Natural wear of the oxygen sensor (service life roughly 100,000 km).
- A faulty heater circuit (see also P0135).
- Sensor poisoning (after silicone sealant use, or oil/coolant entering the exhaust).
- A leak in the exhaust ahead of the sensor.
- A wiring or connector fault.
- An air leak, faulty injectors, low fuel pressure.
- A faulty PCM (rare).
Symptoms: increased fuel consumption, rough running, possible P0171, poorer performance.
P0135 / P0141 — Oxygen Sensor Heater Circuit (B1S1 / B1S2)
Meaning: The PCM has detected a fault in the oxygen sensor heater circuit. P0135 — front sensor (before the converter); P0141 — rear sensor (after the converter). The heater is needed to bring the sensor up to operating temperature (around 300 °C) quickly after start-up.
Possible causes:
- An open heater element inside the sensor itself (the most common cause).
- An open or short in the heater supply circuit.
- A blown fuse in the sensor circuit.
- Heater element resistance out of spec (universal sensors are often fitted).
- A faulty driver in the PCM (rare).
Symptoms: increased fuel consumption (especially early in a trip before warm-up), possible P0171, fluctuating idle on a cold engine. Symptoms get worse in cold weather.
Tip for the technician: measure the heater resistance directly at the sensor connector — normal is 2–15 Ω (model-dependent). If the sensor looks fine, check the supply and ground at the connector from the PCM side.
P0171 — System Too Lean (Bank 1)
Meaning: The PCM has determined that the mixture is too lean — the engine is getting more air than needed, or less fuel. Fuel Trim has moved out of the allowable range toward enrichment. This is one of the most common codes on Mitsubishi.
Common on: Lancer 9/10, Outlander I/II/III, ASX, Colt, Galant, Eclipse Cross — effectively all petrol Mitsubishis.
Possible causes:
- An intake air leak (a cracked PCV hose, manifold gasket, intake pipe).
- A dirty or faulty MAF sensor.
- A faulty PCV/crankcase ventilation valve (a classic 4B11/4B12 problem).
- Clogged injectors.
- Low fuel pressure (a worn fuel pump, a clogged filter).
- A faulty fuel pressure regulator.
- A sticking EVAP purge valve.
- A faulty front oxygen sensor / AFS.
Symptoms: rough idle, increased fuel consumption, misfires, hard hot starting, Check Engine.
Tip for the technician: first check the MAF readings and Long-Term Fuel Trim (LTFT) in Live Data. At idle, a warm 4B11 2.0 should read about 2.5–3.5 g/s. If LTFT is above +10 %, that’s a clear sign of a lean mixture. Always do a visual inspection of all vacuum hoses and the PCV system, and use a smoke machine.
P0201–P0204 — Injector Circuit (Cylinders 1 / 2 / 3 / 4) — Open
Meaning: The PCM has detected an open or no response in the control circuit of the corresponding cylinder’s injector.
Possible causes:
- An open winding in the injector itself.
- A poor contact in the injector connector (oxidation, water).
- An open or short in the wiring from the PCM.
- A faulty injector driver in the PCM (rare, but seen on Lancer IX, Galant).
Symptoms: a misfire in a specific cylinder, uneven running, vibration, Check Engine on. Often paired with P030X (misfire in cylinder X).
Ignition Misfires
P0300 / P0301–P0304 — Random/Multiple Misfire or Misfire in a Specific Cylinder
Meaning: The PCM has detected misfires across several cylinders at once (P0300) or in a specific cylinder (P0301 — cyl. 1, P0302 — cyl. 2, P0303 — cyl. 3, P0304 — cyl. 4). The PCM identifies a misfire from crankshaft rotation irregularity between combustion events.
Common on: all petrol Mitsubishis — especially Lancer 9/10, Outlander I/II/III (4B11/4B12), ASX, Galant, Colt, Carisma (GDI).
Possible causes:
- Worn or fouled spark plugs (the most common cause on MIVEC engines — replacement interval 30,000 km).
- A faulty individual ignition coil (on 4B10/4B11 the coils tend to fail after 100,000 km).
- Low fuel rail pressure.
- Clogged or worn injectors.
- Low compression (worn piston rings, burnt valves).
- Disturbed valve timing (a stretched chain on 4B11/4B12).
- An intake air leak.
- A faulty EGR valve or MIVEC system.
- A faulty crankshaft position sensor (P0335).
- A lean mixture (P0171 + P0300 — a classic pair).
- On GDI engines (Carisma, Galant 4G93 GDI) — coked injectors and intake valves.
Symptoms: engine vibration, rough idle, hesitation under acceleration, a sharp rise in fuel consumption, the smell of unburnt fuel from the exhaust. When a misfire is logged, the PCM cuts fuel to that cylinder to protect the catalytic converter — and as a result you get a “stumbling” engine and a flashing Check Engine.
Tip for the technician: with a flashing Check Engine you must not keep driving — unburnt fuel will destroy the catalytic converter within minutes (and then end up in the oil). Test sequence: inspect/check spark plugs → ignition coils (swap them between cylinders and see whether the code “follows” the coil) → compression → injectors.
P0325 — Knock Sensor Circuit
Meaning: The PCM isn’t receiving a correct signal from the knock sensor — either there’s no signal, or it’s out of the expected range.
Possible causes:
- An open or short in the knock sensor circuit (often a chafed wire near the cylinder block).
- A faulty sensor itself.
- Incorrect sensor torque (a typical repair mistake — over- or under-tightened).
- A faulty PCM (rare).
Symptoms: reduced power (the PCM retards ignition to “safe” angles), increased consumption; under heavy knock — the characteristic pinging under load. On Mitsubishi 4B11/4B12 with coked GDI injectors, P0325 often appears alongside P0300.
P0335 — Crankshaft Position Sensor (CKP) — Circuit Malfunction
Meaning: The PCM isn’t receiving a signal from the crankshaft position sensor, or the signal is incorrect. Without the CKP there’s no way to determine injection and ignition timing — the engine won’t start or will stall.
Possible causes:
- A faulty sensor (an open winding).
- A damaged or contaminated reluctor wheel on the crankshaft.
- An open/short in the wiring, an oxidised connector.
- An incorrect air gap between the sensor and the reluctor wheel (snagged on a foreign object).
Symptoms: the engine won’t start, stalls while driving (often when warm), unstable rpm, may show no rpm on the tachometer while cranking.
P0340 — Camshaft Position Sensor (CMP) — Circuit Malfunction
Meaning: The PCM isn’t receiving a signal from the camshaft position sensor, or can’t synchronise it with the CKP signal. On MIVEC engines the CMP signal is needed for phase control — losing it makes the PCM disable MIVEC and enter limp mode.
Possible causes:
- A faulty sensor.
- An open/short in the circuit.
- Contamination of the reluctor segment on the camshaft.
- A stretched timing chain (the reluctor mark has shifted).
Symptoms: hard starting, hesitation, power loss, possibly a no-start. Often together with P0011 (where MIVEC is present).
Electronic Throttle and Accelerator Pedal (ETCS)
Since the early 2000s Mitsubishi has used an Electronic Throttle Control System. The throttle body has a control motor and two position sensors; the accelerator pedal contains two independent sensors (APS). If the PCM sees a mismatch or an incorrect signal, the car enters limp mode — rpm and power are limited and pedal response drops out.
P0638 — Throttle Actuator Control Range/Performance
Meaning: The PCM has detected that the actual throttle position doesn’t match the commanded one — the throttle motor isn’t following the command.
Possible causes:
- A carboned-up throttle body (the classic issue — the throttle physically can’t move freely).
- A faulty throttle motor.
- An open or short in the motor circuit.
- A faulty throttle power relay (P0657).
- A faulty PCM (rare).
Symptoms: the engine enters limp mode — rpm limited to 1200–1500, the pedal doesn’t respond normally, Check Engine and ASC/ASTC are on.
Tip for the technician: cleaning the throttle body with a dedicated cleaner followed by adaptation (relearn) via the scanner resolves P0638 in roughly 60 % of cases. After cleaning, always perform the reset and relearn procedure.
P0642 — Throttle Position Sensor — Reference Voltage Low
Meaning: The PCM detects that the +5 V reference supplied to the throttle position sensor is below normal (usually under 4.7–4.8 V).
Possible causes:
- A +5 V-to-ground short in the wiring or in one of the sensors sharing that same line.
- A faulty TPS.
- A faulty PCM (the internal +5 V regulator has failed).
Symptoms: limp mode, a set of related codes for sensors sharing the common +5 V reference.
Tip for the technician: with P0642, disconnect the sensors on the +5 V line one by one and watch which one makes the line recover. The PCM pinout and the list of sensors are easy to view in the MotorData PinData section.
P0657 — Throttle Actuator Control Relay Circuit — Malfunction
Meaning: The PCM can’t switch the relay that powers the electronic throttle motor on or off.
Possible causes:
- A faulty relay itself (ETV relay, sometimes built into the junction block).
- A blown throttle circuit fuse.
- An open or short in the relay control circuit.
- A faulty PCM.
Symptoms: the throttle actuator doesn’t work, the engine is in limp mode with reduced rpm. The code often appears only after a cold start.
Engine Control Module (PCM) and Typical Internal Codes
P1240 / P1242 / P1243 — Ignition Timing Plausibility Check / Monitoring System Failsafe / Query-Response Error
Meaning: These are Mitsubishi internal control-system codes. The PCM continuously checks itself with internal “plausibility tests”: whether the commanded ignition angle matches the actual one, and the torque-monitoring cross-check with the ABS/ASC module. If the checks fail, one of the P124x codes is set. These codes are very characteristic of Lancer X and Outlander with 4Bxx engines.
Possible causes:
- An accompanying fault (the primary code): misfires, throttle faults, sensor problems.
- A faulty PCM (if there are no primary codes at all).
- A drop in system voltage (a weak battery, a poor PCM ground).
Symptoms: limp mode, rpm and power limited.
Tip for the technician: P1240–P1243 are never diagnosed in isolation. First clear all primary codes (throttle, sensors, MIVEC, injectors), then erase the memory — and P124x usually disappears. If it doesn’t, and there are no primary codes, check the PCM power and ground against the diagram.
P1603 — PCM Back-up Supply Line
Meaning: The PCM has detected missing or low voltage on the constant back-up supply line (“memory”, +B BATT), which preserves adaptations, learned values and codes with the ignition off.
Possible causes:
- A blown PCM back-up fuse (often in the underhood box, marked ECU/ECM).
- An open back-up supply wire.
- A recent battery disconnect (the code is sometimes stored as passive).
- An oxidised PCM connector.
- A weak battery, a voltage drop during cranking.
Symptoms: adaptations reset constantly (every start feels like “the first”), faults across many systems, radio and clock settings reset. On Lancer X, P1603 often appears together with U-codes (see below).
P0603 — Control Module EEPROM Error
Meaning: The PCM has detected an error reading or writing the non-volatile memory that stores adaptations, immobiliser codes and learned values.
Possible causes:
- Loss of PCM back-up power (see P1603).
- A faulty PCM itself (an internal memory defect).
- The aftermath of an incorrect reflash attempt (chip tuning).
Symptoms: adaptations reset, immobiliser problems, possibly a no-start.
P0606 — PCM Processor Fault
Meaning: The PCM has detected an internal processor or software fault. One of the few codes that can point to a fault in the control module itself.
Possible causes:
- An internal PCM fault.
- Low PCM supply voltage (a poor contact in the power or ground circuit).
- The aftermath of a system-voltage sag during a start on a weak battery.
- A short in actuator control circuits (an overloaded driver).
Symptoms: Check Engine, possibly several systems failing at once, rough running. Before replacing the PCM, always thoroughly check all power and ground circuits.
P0622 — Generator Field Control Circuit (Terminal “FR”)
Meaning: The PCM receives field-load information from the alternator over the “FR” line. If the signal is incorrect, P0622 is set. On Mitsubishi with a “smart” alternator (Lancer X, Outlander, ASX, Galant) the PCM takes part in controlling charging voltage.
Possible causes:
- A faulty alternator (voltage regulator).
- An open or short in the FR wire between the alternator and the PCM.
- An oxidised alternator connector.
- Battery undercharging / overcharging.
Symptoms: Check Engine, sometimes the battery light, erratic charging-system behaviour.
P0630 — VIN Not Programmed in the PCM
Meaning: After PCM replacement or reflashing, the VIN-writing procedure into the module’s memory wasn’t performed. The code is purely procedural and doesn’t affect engine operation, but it interferes with other self-diagnosis tests passing.
Tip for the technician: cleared with a dealer scanner or compatible equipment supporting Mitsubishi VIN writing.
Vehicle Speed Sensors and Transmission
P0500 — Vehicle Speed Sensor (VSS) — Circuit Malfunction
Meaning: The PCM isn’t receiving a correct speed signal. On modern Mitsubishi the speed signal comes from the wheel sensors via the ABS module and is sent over CAN.
Possible causes:
- A faulty transmission speed sensor (on older models with a mechanical/pulse sensor).
- A faulty ABS wheel sensor.
- A CAN break between the ABS module and the PCM.
- A faulty ABS module.
Symptoms: a dead speedometer, cruise control failure, ASC/ASTC disabled, possible transmission jerking during shifts.
P0705 / P0750 / P0753 — Transmission Range Sensor Fault / Shift Solenoid — Open/Short
Meaning: P0705 — an incorrect signal from the transmission range sensor (the inhibitor/park-neutral switch). P0750 — shift solenoid 1 of the electronic transmission control; P0753 — the clutch control solenoid for 1st gear.
Common on: Lancer, Outlander, Galant, Pajero with INVECS-II automatics; INVECS-III JF011E CVTs (Outlander II/III, ASX — the same unit as on the Nissan Qashqai).
Possible causes:
- A faulty solenoid (an open winding, mechanical sticking).
- A valve body contaminated with wear debris (ATF not changed for a long time).
- An open or short in the solenoid wiring.
- An oxidised transmission harness connector.
- A faulty TCM.
Symptoms: the transmission “sticks” in one gear, jerking, limp mode (3rd gear), the AT light on.
FAQ
How do I read Mitsubishi trouble codes myself?
Plug an OBD2 scanner into the diagnostic connector (usually under the dash on the driver’s side), turn the ignition on, and read the stored codes. Write down every code along with the freeze-frame data before clearing anything — that’s where most of the diagnostic clues are. A generic ELM327-class adapter is enough to read codes, but for manufacturer-specific codes (the P1xxx range) and live actuator tests you’ll want software with Mitsubishi coverage.
Can I keep driving with the Check Engine light on?
It depends on the code. A steady light usually means you can drive carefully to a workshop, but a flashing Check Engine — typically a misfire (P0300–P0304) — means stop as soon as it’s safe: raw fuel can destroy the catalytic converter within minutes. Codes that put the engine into limp mode (throttle and PCM faults) also call for prompt attention.
Why does one fault throw several codes at once?
A single physical defect — an air leak, a weak battery, a poor ground — can disturb many circuits at the same time and set a cluster of seemingly unrelated codes. That’s why you diagnose the root cause, not each code separately, using the wiring diagram, Live Data and the ECU pinout together.
Do Mitsubishi codes differ between markets?
Yes. ECU pinouts and the operating logic of EGR, MIVEC and the throttle body can differ between JAP, EUR, GEN and USA versions of the same model. Always work from the wiring diagram and pinout for the exact model, engine and year — that’s exactly what MotorData Automotive Electrics provides.
Where can I find wiring diagrams and pinouts for these codes?
In MotorData Automotive Electrics: for each code it has interactive colour wiring diagrams, component-location diagrams, junction-block layouts, ECU pinouts (PinData) and DTC set conditions for the specific model, engine and year.
Diagnose Mitsubishi Faster with MotorData
A trouble code only points you to a subsystem — the actual fix comes from the wiring diagram, the ECU pinout and the DTC set conditions for your exact car. MotorData Automotive Electrics gives auto electricians, diagnostic techs and workshop mechanics interactive colour wiring diagrams, component-location and junction-block diagrams, PinData pinouts and characteristic faults for dozens of Mitsubishi models from 1986 to 2023, plus more than 60,000 DTC codes across all brands.
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