ECU & Outputs Trouble Codes: List & Fixes

P06xx codes come from the engine or powertrain control module itself and from the output circuits it drives: internal memory or processor checks, sensor reference voltage and driver circuits for relays and actuators. Before condemning an expensive module, check battery condition, ground connections and fuses, and ask a dealer whether a software update exists. A replacement module often has to be programmed to the vehicle.

54Codes

2.9Average severity

15%High or critical

22%DIY-friendly

Severity distribution

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P0562 Powertrain The engine computer sees too little supply voltage – usually a charging, battery or ground… Moderate P0606 Powertrain The engine computer failed its own internal self-test – check its power and grounds before… Moderate P1000 Ford · Powertrain Ford's computer hasn't finished all its self-tests yet. It's a status message, not a fault. Minor P0217 Powertrain The engine overheated. Stop driving: continuing can warp the head, blow the head gasket… Critical P0219 Powertrain The engine was spun faster than its maximum allowed rpm, usually by a missed shift or wheelspin. Moderate P0600 Powertrain The engine computer lost a dedicated data link to another module, most often the transmission… Moderate

All codes (54)

All Severity 3+ Severity 4+

P0687 Powertrain The main relay control line sits at battery voltage – the relay may never switch on or never… Moderate P0690 Powertrain The ECM still sees power coming through its main relay when the relay should be off – often… Low P069E Chevrolet · Powertrain The fuel pump control module stored its own fault and asked the engine computer for the check… Moderate P06DD Powertrain The ECM commanded an oil pressure change and the measured pressure didn't respond – check… High P1000 Ford · Powertrain Ford's computer hasn't finished all its self-tests yet. It's a status message, not a fault. Minor P1217 Nissan · Powertrain Nissan's ECM saw engine coolant get hotter than it should, usually because the radiator fan… Critical P1298 Honda · Powertrain The ELD signal that tells the PCM how much current the car is drawing is stuck too high. Low P1602 Volkswagen · Powertrain The engine computer saw its constant battery feed drop too low – usually a disconnected, flat… Low P1607 Honda · Powertrain The Honda engine computer's self-test found a fault inside its own circuitry. Moderate P1610 Nissan · Powertrain After repeated failed immobilizer checks, the Nissan ECM has locked itself and won't let… Moderate P1612 Nissan · Powertrain The Nissan ECM and the immobilizer (IMMU or BCM) couldn't complete their ID exchange, so… Moderate P1614 Nissan · Powertrain The Nissan immobilizer couldn't read the transponder chip in the key, so the engine isn't… Moderate P1626 Chevrolet · Powertrain The engine computer lost the 'OK to fuel' signal from the Chevy anti-theft system, so it may… Moderate P1631 Chevrolet · Powertrain The engine computer received the wrong anti-theft password, so it blocks starting or fuel. Moderate P1633 Ford · Powertrain Ford's PCM lost its constant battery feed, so the memory holding learned fuel, idle and shift… Low P1682 Chevrolet · Powertrain The engine computer's two ignition power feeds disagree, which can cause stalling or Reduced… High P1684 Jeep · Powertrain An informational code: your Jeep's PCM lost battery power at some point in the last 50 engine… Minor P1690 Hyundai · Powertrain The engine computer asked the SMARTRA immobilizer unit to check your key and got no answer back. Moderate P1693 Kia · Powertrain The immobilizer couldn't read a valid code from the chip in your Kia key, so the engine isn't… Moderate P2502 Powertrain The ECM distrusts the charging system – no output, wrong voltage or an implausible alternator… Moderate P2503 Powertrain The alternator can't reach the voltage the ECM asks for – usually a worn alternator or slipping… Moderate P2504 Powertrain The charging system is overcharging – too much voltage can boil the battery and damage… High P25A2 Chevrolet · Powertrain The brake module stored a fault and asked the engine computer to turn on the check engine light. Moderate P26B7 Ford · Powertrain The PCM sees an open circuit to the electric coolant bypass valve on Ford's 1.6L EcoBoost… Moderate

Subsystems

Fuel & Air Metering 193 Emission Controls 97 Ignition & Misfire 66 Speed & Idle Control 57 Transmission 57 Module Communication 43 Brakes, ABS & Chassis 36 Body Systems 31 Hybrid / EV 14