Car Fault Code and ECU Module Directory

FAULT CODES · ECU FAMILIES · DIAGNOSTIC ROUTES

Find a starting point for an automotive fault-code or module enquiry. Search the complete code from your scanner, or browse the guides below. Each article explains the information needed before deciding whether a vehicle needs diagnostics, electronic repair or programming.

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How to use your diagnostic trouble code

Keep every character, the reporting controller and any suffix or additional information code. Include the vehicle make, model, year and powertrain. Similar-looking codes can have different manufacturer-specific meanings. A stored code describes a detected condition; it does not automatically prove that the named module has failed.

The directory covers selected verified code families. If your code is not listed, send the complete scan for an enquiry. Do not substitute a nearby number or use another model’s repair instructions.

More fault codes, grouped by system

Choose a group to see the code guides. Keep the complete scanner description, including any suffix, when asking about a fault.

Sensor supplies and engine circuits

• Shared sensor supply faults P0641, P0642 and P0643
• Checking glow-plug module and circuit faults P0670 and P0671-P0674
• Brake-switch signal faults P0571, P0572 and P0573
• MAP sensor readings and wiring with P0105-P0109 faults
• Ignition coil circuits and ECU testing with P0351-P0356
• P0110-P0114 intake-air temperature faults after engine work
• EVAP purge-valve electrical faults P0443, P0444 and P0445

Transmission selectors and lock-up

• Gear selector recognition faults P0705-P0709
• Checking torque-converter lock-up and TCU operation with P0741

Body modules and comfort networks

• VAG 01330 convenience module J393 supply-voltage faults
• VAG 01331 driver-door wiring and communication faults
• VAG 01336 comfort CAN and single-wire operation

Battery supply and cooling-fan electronics

• Porsche Cayenne P0480 with cooling-fan faults and a flat battery
• VAG 00446 functions limited by low voltage

Browse fault-code guides

Existing diagnostic guides

P0606 processor faults · U0100 and U0101 · BMW FRM lighting faults · Water-damaged electronics

Body, brake, airbag and dashboard modules

For a BCM, BSI, FRM, SAM, ABS/ESP, SRS, instrument cluster or gateway enquiry, include the controller name and complete manufacturer-specific fault text. An engine-only scan may not contain the information needed. We do not assign a universal meaning to every B-code, C-code or manufacturer-specific number.

BCM/BSI · FRM/SAM · ABS/ESP · SRS assessment · Instrument clusters · Network and complex diagnosis

Engine and sensor fault-code guides

Use the exact code and full diagnostic report. These linked guides distinguish the recorded condition from the cause and explain what evidence to send.

P0300, P0301, P0302, P0303, P0304 — misfire

P0335, P0340 — crankshaft and camshaft signals

P0100, P0101 — air-mass measurement

P0115, P0118 — coolant-temperature circuit

P0400, P0401, P0402 — EGR flow

DPF differential-pressure sensor warnings

P2138 — pedal signal correlation

P0130, P0135 — oxygen sensor and heater

P0201, P0202, P0203, P0204 — injector circuits

P0299, P0234 — boost pressure

Body electronics, lighting and mild hybrids

Automatic Wipers or Lights Not Working After a Windscreen Replacement

Water damage, identification and coding for LED headlight modules

Camera and Radar Warnings After Windscreen, Alignment or Accident Repairs

Identifying 48-volt mild-hybrid batteries, converters and starter-generators

Fuel-pressure codes P0087, P0088 and P0191

Distinguish a recorded pressure condition from a confirmed ECU failure. Read the fuel-pressure code guide for the code differences and enquiry checklist.

EV charging, battery management and software

Getting help with AC and DC electric car charging faults · How battery management systems track charge and battery health · EV low-voltage warnings and the battery, DC/DC converter and electronics · What to record when a fault appears after a vehicle software update · How zonal controllers are changing car electronics

Dashboard, ABS, key signals and hybrid isolation

• U0155 / 01317 — instrument cluster communication
• 01316 — ABS communication and fault memory
• 00778 — G85 steering-angle diagnosis
• 00532 — supply voltage B+
• 01176 — key signals and immobiliser diagnosis
• P0AA6 / P1FFF / P1F0E / P0DAA — hybrid isolation and charging

Tyre-pressure warnings and sensor learning

• Programming and relearning new TPMS sensors
• 01521 tyre-pressure sensor signals
• 02214 tyre-pressure warning and calibration
• 01325 identify the TPMS system and J502

ABS sensors, pump supplies and steering setup

• 00283 / 00285 / 00287 / 00290 wheel-speed signals
• 01435 G201 brake-pressure sensor
• 01276 V64 ABS pump electrical checks
• 02546 steering limit-stop adaptation
• 01309 J500 steering communication
• 01423 G200 lateral acceleration sensor

ECU and TCU testing, coding and programming

• P2711 DSG gear disengagement and TCU assessment
• P1740 / P0716 DSG temperature, speed signals and wiring
• P1746 TCU power relay and supply checks
• P1647 ECU coding after replacement
• Voltage and current waveforms in ECU output testing
• Preparing for J2534 programming at your garage
• Intermittent ECU wake-up and fuse-current testing

EV and hybrid case reviews and garage referrals

• Toyota Auris hybrid cooling case with P0A82-123
• P0A94 / P324E / P0A1A / P3004 Prius inverter codes
• Renault Zoe heat-pump live-data case review
• ECU, TCU, EV and hybrid referrals from UK garages

Engine signals, transmission ratios and coolant-pump circuits

• P0322 missing engine-speed signal
• P0341 camshaft signal and timing context
• P2122 accelerator pedal signal low
• P0731 first-gear ratio and TCU enquiries
• P0722 missing transmission output-speed signal
• P261A pump open circuit and campaign history

EV charging, hybrid start authorisation and advanced diagnostics

• P2600 electric coolant-pump circuits
• EV charging plug lock and release faults
• EV Control Pilot communication
• Volvo high-voltage heater bulletin for U133A93
• Kia Niro with no READY and no stored code
• DoIP communication with newer modules

Engine temperature, throttle, timing and starting circuits

• P0116 coolant-temperature plausibility
• P0121 throttle-position plausibility
• P0135 oxygen-sensor heating circuit
• P0325 knock-sensor wiring and mounting
• P0230 fuel-pump primary circuit
• P0650 engine warning-lamp control
• P0016 camshaft and crankshaft correlation
• P0615 starter-relay and no-crank enquiries

Transmission temperature, solenoid and clutch-control codes

• P0711 transmission-temperature signal
• P0743 torque-converter clutch electrical fault
• P0753 shift-solenoid electrical fault
• P0810 clutch-position control and adaptation
• P0902 clutch-actuator circuit low

High-voltage interlocks, converter signals and 48-volt systems

• P0A0D high-voltage interlock warning
• P0AFA battery-system voltage warning
• P0A1F Bentayga W12 48-volt chassis example
• P0A09 DC/DC converter status circuit
• P0A4B generator-position sensing
• P0A7A generator-inverter performance
• P0A0F hybrid engine-start failure

What if no code is stored?

Describe the symptoms and when they happen. Examples include a non-starting car, intermittent cutting out, missing drive, warning lights, failed lights or a controller that will not communicate. Keep the original module and note battery, wiring or programming work. The repair finder in our main library can help select an enquiry route.

Send AXION your diagnostic details

For a Didcot workshop enquiry or a suitable UK postal module assessment, send the vehicle model, year, engine or gearbox, full module label, complete scan report and a description of what happened. Include previous battery work, programming, water ingress or replacement parts. Please agree suitability before removing or posting a unit.

Discuss the fault with AXION →

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