What is CID 21:
CID 21 refers to a problem with the engine's intake air temperature sensor. The ECM detects an out-of-range signal from the sensor, which can cause poor fuel combustion, reduced engine power, and lower fuel efficiency.
Why This Happens:
- Faulty intake air temperature sensor.
- Shorted or damaged wiring in the sensor circuit.
- Loose or corroded sensor connectors.
- ECM misinterpretation of the sensor’s data.
- Air intake blockage or contamination.
How to Fix It:
- Inspect the intake air temperature sensor for damage or malfunction.
- Test the sensor’s voltage and resistance to ensure proper operation.
- Check wiring and connectors for damage or corrosion.
- Replace the faulty sensor if necessary.
- Inspect the air intake system for blockages or contamination.
How to Avoid It Before It Happens:
- Perform regular air intake system inspections.
- Keep the intake air temperature sensor clean and calibrated.
- Regularly check wiring and connectors for wear or corrosion.
- Perform diagnostic checks to monitor sensor data.
- Clue’s fuel management services track intake air systems and help prevent malfunctions before they affect engine performance.
