Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- ACTIVE DTC
- Turn the ignition on.
- With the scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
- CHECK THE (K21) IAT SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
- Turn the ignition off.
- Disconnect the Intake Air Temperature Sensor harness connector.
- Disconnect the PCM C2 harness connector.
- Measure the resistance between ground and the (K21) IAT Sensor Signal circuit in the Intake Air Temperature Sensor harness connector.
Is the resistance above 10k Ohms?
Yes
- Go To 3
No
- Repair the (K21) IAT Sensor Signal circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK FOR THE (K21) IAT SENSOR SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT
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- Measure the resistance between the (K21) IAT Sensor Signal circuit and the (K900) Sensor Ground circuit in the IAT Sensor harness connector.
Is the resistance above 10k Ohms?
Yes
- Go To 4
No
- Repair the (K21) IAT Sensor Signal circuit for a short to the (K900) Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Measure the resistance between the (K21) IAT Sensor Signal circuit and the (K900) Sensor Ground circuit in the IAT Sensor harness connector.
- INTAKE AIR TEMPERATURE SENSOR
- Turn the ignition off.
- Reconnect the PCM C2 harness connectors.
- Turn the ignition on.
- Using the scan tool, read the IAT Sensor signal voltage.
Is the voltage above 4.8 volts with the Intake Air Temperature Sensor harness disconnected?
Yes
- Replace the Intake Air Temperature Sensor in accordance with the service information. Refer to SENSOR, AIR TEMPERATURE, INLET, REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 5
- POWERTRAIN CONTROL MODULE (PCM)
- Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Intake Air Temperature Sensor and the Powertrain Control Module (PCM).
- Look for any chafed, pierced, pinched or partially broken wires.
- Look for broken, bent, pushed out or corroded terminals.
- Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
- Look for the data to change or for the DTC to reset during the wiggle test.
- Perform any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Replace and program the Powertrain Control Module (PCM) in accordance with the service information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.