What it means
The ECM detects a range/performance fault on the a/c refrigerant temperature sensor a circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
A/C refrigerant temperature sensor A provides a temperature reading that the control module uses to manage A/C operation. This code sets when the reading is implausible or outside the expected range for operating conditions, rather than simply identifying a particular high or low circuit signal.
Common causes
Most likely first.
- Sensor characteristic drifted
- Sensor mounting displaced
- Sensor element aged beyond calibration window
Symptoms
- A/C warning light or check-engine light
- Air conditioning may cool inconsistently or poorly
How to diagnose it
- Use freeze-frame data and live readings to compare sensor A's temperature with ambient temperature and other available refrigerant readings.
- Inspect sensor A's mounting and position, then check its connector and wiring for damage or poor contact.
- Check the sensor A circuit for shorts or excessive resistance using the manufacturer's wiring information.
- Observe sensor A's reading as A/C operation changes and compare its response with the manufacturer's specification.
- If mounting and wiring are correct, test sensor A for drift and replace it if it fails the specified checks.
Common fixes
- Reposition sensor A securely if it has moved from its specified location.
- Repair damaged or high-resistance wiring in the sensor A circuit.
- Clean or repair poor connector contact.
- Replace sensor A if its reading remains outside the manufacturer's specified range.
Can I keep driving?
The control module may limit A/C operation because sensor A's temperature response is implausible, leading to inconsistent or poor cooling. Driving is generally possible, but fix the fault if demisting or cabin comfort is compromised.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.