P00A4
Charge Air Cooler Temperature Sensor Circuit Intermittent/Erratic Bank 2.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 0
- AreaFuel and air metering, auxiliary emission controls
- A4
- FaultThe specific fault in that area
What it means
P00A4 means the engine control unit has detected an intermittent or erratic signal from the charge air cooler temperature sensor circuit on bank 2. The signal jumps, drops out or changes implausibly quickly compared with what the other intake and temperature sensors suggest. The control unit uses this reading to manage boost, fuelling and ignition, so a poor signal can affect performance.
Symptoms
- Engine warning light on
- Loss of power or reduced boost, sometimes only intermittently
- Car may go into limp mode
- Hesitation or poor acceleration under load
- Slightly higher fuel consumption
- Fault comes and goes, often with vibration or heat
Possible causes
- Loose, corroded or damaged connector at the bank 2 charge air cooler temperature sensorlikely
- Chafed, stretched or broken wiring in the sensor circuit (open circuit, intermittent short to earth or voltage)likely
- Failing charge air cooler temperature sensor with an erratic outputlikely
- Water, oil or coolant contamination in the connector or sensorpossible
- Poor earth or reference voltage supply shared with other sensorspossible
- Fault within the engine control unit sensor inputrare
How to diagnose
- Read all stored and pending codes and note the freeze frame data, including engine load, intake air temperature and engine speed at the time of the fault
- Check for other temperature or boost sensor codes that might point to a shared wiring or supply fault
- Locate the bank 2 charge air cooler temperature sensor (position depends on model and engine) and inspect the sensor, connector and nearby wiring for damage, rubbing, heat damage or moisture
- Disconnect the connector and check the terminals for corrosion, bent pins and poor tension, then reconnect firmly
- With the engine running, view the live sensor reading and gently wiggle the connector and harness to see if the value jumps or drops out
- Compare the live reading with other intake air temperature readings on a cold engine; they should be close
- Check the sensor circuit for continuity, short circuits and the correct reference voltage and earth against the manufacturer's wiring diagram and specification
- Measure the sensor resistance at a known temperature and compare it with the specification for your model
How to fix
- Clean and refit or replace a corroded or loose connector and repair any damaged terminals
- Repair or replace damaged wiring in the sensor circuit, securing the harness away from heat and rubbing points
- Replace the bank 2 charge air cooler temperature sensor if its readings are erratic or out of specification
- Rectify any water or oil ingress and fix the source of the contamination
- Repair faulty earth or supply connections, then clear the code and road test to confirm it does not return
Can I keep driving?
Medium severity
The car can usually be driven for a short time, but power may be reduced and the fault may worsen. Have it checked soon, and avoid heavy load or towing until it is fixed.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.