Fault-Code Library

The ECU sees the crankshaft and camshaft signals outside their expected relationship.

Measured fuel pressure fell below the pressure requested by the engine controller.

Airflow reported by the MAF sensor does not agree with the ECU's calculated operating conditions.

Fuel trim has reached a lean threshold because the ECU is adding more fuel than expected.

Boost pressure exceeded the ECU's permitted target for the operating condition.

The engine did not produce the boost pressure requested by the controller.

Misfires are occurring across more than one cylinder or without one consistent cylinder pattern.

Measured or inferred EGR flow is lower than the controller expects.

Upstream and downstream oxygen-sensor behavior suggests insufficient catalyst oxygen-storage performance.

The ECU calculates that particulate-filter performance is below its required threshold.

The intake-runner position signal is outside the range expected by the controller.

The SCR system is not reducing NOx emissions as effectively as the ECU expects.

The reductant system is not meeting the performance expected by the emissions controller.

A NOx sensor signal or its controller behavior is outside the expected operating range.

The pressure signal used to calculate DPF restriction is implausible or outside range.

A diesel particulate filter regeneration took too long or did not complete as expected.

Calculated soot loading has reached a level that requires diagnosis before normal operation can continue.

One or more modules stopped receiving expected messages from the engine controller.

The ECU sees an intake-air temperature signal that is higher voltage than expected, often interpreted as an unrealistically cold reading.

The engine is taking too long to reach expected operating temperature or is running cooler than the ECU expects.

The upstream oxygen or lambda sensor signal is implausible, missing, or outside the control range expected by the ECU.

Fuel trim has reached a rich threshold because the ECU is removing more fuel than expected.

The fuel-vapor system cannot hold the small vacuum or pressure change expected during the leak test.

Idle speed is higher than the ECU's target after it has reached the limit of normal control correction.

The engine controller has been told by the transmission controller that a gearbox-related fault is present.

The gearbox input and output speeds do not match the gear ratio the controller expected.

The ECU detects a lean condition mainly at idle, where small air leaks have a larger effect on mixture control.

A chassis or suspension control module has detected an implausible pressure, height, or control-state condition.

Modules on the vehicle network are not receiving expected messages from the ABS or stability-control controller.

The intake camshaft is more advanced than the ECU expects for the current operating condition.

The exhaust camshaft position is more advanced than commanded or is slow to return to the expected position.

The MAF sensor signal is lower than expected for the engine speed and load.

The coolant-temperature signal is implausibly high voltage, often read by the ECU as extremely cold coolant.

The upstream oxygen sensor heater circuit is not operating as expected.

The downstream oxygen sensor heater circuit is not reaching expected operation.

The ECU detected repeated combustion misfires on cylinder 1.

The ECU detected repeated combustion misfires on cylinder 2.

The ECU detected repeated combustion misfires on cylinder 3.

The ECU detected repeated combustion misfires on cylinder 4.

The ECU is not receiving a plausible signal from the knock sensor circuit.

The ECU is missing or cannot trust the crankshaft position signal.

The ECU is missing or cannot trust the camshaft position signal on bank 1.

The ECU does not see the expected oxygen-sensor response when the secondary-air system runs on cold start.

The fuel-vapor purge system flow is not matching the ECU's commanded behavior.

The fuel-vapor system has a large leak or cannot seal during its self-test.

The fuel-vapor system has a very small leak during the ECU's leak test.

System voltage fell below the level expected by the ECU during operation.

The engine controller detected an internal processor or control-module fault.

The transmission controller cannot trust the input or turbine speed signal.

The torque converter clutch is not locking as expected or slip remains too high.

The transmission controller detected an electrical or hydraulic problem with shift solenoid A.

The transmission controller sees lower hydraulic pressure than required for reliable clutch or gear operation.

The ECU detects extra unmetered air entering the intake system.

The ECU detects an electrical fault in the heater circuit for the upstream oxygen sensor.

Throttle position, manifold pressure, and measured airflow do not agree with one another.

Fuel pressure is dropping at a rate that the ECU interprets as a major leak or excessive internal loss.

The rail-pressure signal is implausible or does not follow commanded pressure correctly.

The charge-pressure signal is outside the expected range or disagrees with operating conditions.

The ECU detects more EGR flow than requested, often because the valve is not closing correctly.

The ECU cannot control or verify the primary electric cooling-fan circuit.

The ECU sees an electrical fault in an exhaust-temperature sensor used to protect the turbo and emissions system.

The engine controller detects a fault in the glow-plug module or its main control circuit.

The glow-plug circuit for cylinder 1 has an electrical or current-consumption fault.

Measured intake airflow does not match the ECU model across the expected operating range.

The redundant throttle-position signals disagree beyond the permitted tolerance.

The complete turbocharging system is not producing or controlling boost as expected.

The high-pressure fuel regulator cannot maintain the pressure requested by the ECU.

The ECU has detected that DPF regeneration is occurring more frequently than expected.

The reported turbo actuator position does not match the requested or mechanically possible range.

The ECU detects an open circuit in an auxiliary or electrically driven coolant-pump circuit.

The SCR system calculates excessive NOx emissions associated with reductant quality or dosing performance.

Other control modules cannot communicate reliably with the transmission controller.

One or more modules have lost communication with the body control module.

The exhaust-camshaft and crankshaft signals on bank 1 are outside their expected relationship.

Turbo actuator or boost-control response is outside the range expected by the ECU.

Measured fuel-rail pressure exceeds the value requested by the engine controller.

The engine controller recorded coolant temperature above its safe operating threshold.

The ECU detects repeated combustion failure specifically on cylinder 5.

The ECU detects an electrical fault in the EGR valve or its control circuit.

The engine controller has lost or detected corruption in memory retained when the ignition is off.

The selected gear or park/neutral signal is implausible for the transmission's actual state.

The upstream oxygen sensor on bank 1 remains at a lean indication despite ECU correction.

Another control module has received implausible or corrupted information from the engine controller.

The MAP sensor signal does not match the pressure expected from throttle position, boost, engine speed, and airflow.

The ECU sees a throttle or accelerator-position signal that is outside the expected relationship.

The exhaust-pressure sensor signal is implausible for engine load, speed, and DPF pressure conditions.

A shared 5-volt reference circuit for engine sensors is missing, shorted, or pulled out of range.

The ECU detects an open circuit in the intake runner or swirl-flap control system.

The coolant temperature behavior is outside the expected warm-up or operating range.

The ECU has calculated excessive ash or restriction in the diesel particulate filter.

The transmission controller detects incorrect hydraulic pressure response from a pressure-control solenoid circuit.

The brake-control module detects a fault in the ABS pump motor circuit or its power supply.

Another module is receiving implausible or corrupted data from the ABS or stability-control module.

The ECU detects an electrical fault in the ignition coil A control circuit.

Vehicle speed information is implausible compared with wheel speed, gearbox, or engine operating data.

The transmission controller does not receive a plausible output shaft speed signal.

The transmission controller cannot see the expected intermediate shaft speed signal.

The ABS module sees an implausible or missing signal from the right front wheel-speed sensor circuit.

The transmission controller detected a shift event that did not match the commanded gear change.

The downstream NOx sensor signal is outside the range expected by the SCR system.

The ABS module sees an implausible or missing signal from the left front wheel-speed sensor circuit.