What it means
The ECM detects a intermittent/erratic fault on the a/c compressor control module internal 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
Internal temperature sensor A monitors the temperature inside the A/C compressor control module. This code sets when its signal jumps or drops unpredictably, so the module cannot use it consistently to manage compressor operation; a loose connector or unstable ground can cause this pattern.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- A/C warning light may come on
- Air conditioning may cool intermittently
- A/C operation may be limited or disabled
How to diagnose it
- Check freeze-frame data and live sensor A readings, and note whether the fault occurs during compressor operation or after vibration or temperature changes.
- Inspect sensor A's connector for incomplete seating, corrosion, loose terminals, or signs of movement, and check the nearby harness for chafing.
- With the vehicle safely stationary, gently move the accessible sensor wiring while monitoring the scan-tool reading for dropouts.
- Check the sensor ground and reference circuits for unstable connections using the manufacturer's procedure.
- If the wiring and connections remain stable, test sensor A and the compressor control module input as specified by the manufacturer.
Common fixes
- Fully seat and secure the sensor A connector.
- Clean corroded terminals and repair loose connector pins or an unstable ground connection.
- Repair chafed or damaged wiring that causes signal dropouts.
- Replace sensor A or repair the compressor control module only if testing confirms the faulty part.
Can I keep driving?
You can usually drive with the A/C off, but cooling may cut in and out or be disabled. If an EV or hybrid warning appears, follow the vehicle's warning instructions and avoid relying on the compressor until the intermittent fault is resolved.
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.