P037

Diagnostic Trouble Code Chart P037:

Powertrain Control Module (PCM) Sensor Circuit:

CIRCUIT DESCRIPTION
The Intake Air Temperature (IAT) sensor is a thermistor, or variable resistor, that varies resistance based on temperature. As the temperature of the sensor increases, resistance decreases. High temperature will result in low signal voltage. Code P037 sets when the Powertrain Control Module (PCM) sees an IAT sensor reading of 147°C (297°F) when the coolant is less than 100°C (212°F).

TEST CONDITIONS
1. Code P014 and P015 are not set.
2. Engine coolant temperature 100°C (212°F) or less.

FAILURE CONDITION
IAT 147°C (297°F) or greater.

ACTION TAKEN
1. PCM turns "ON" the Malfunction Indicator Lamp (MIL) (Service Engine Soon).
2. PCM substitutes outside air temperature for IAT.
3. Transaxle shift adapts are maintained at current levels.

NOTES ON FAULT TREE
1. If the IAT sensor is shorted, PCM Data PD05 should read 147°C (297°F) or greater. If it does not, then the sensor is not shorted.
2. Checking for CKT 472 shorted to ground. If PCM Data PD05 stays at 147-151°C (297-304°F) with connector C127 disconnected, then CKT 472 is shorted to ground.
3. Checking for a sensor shorted or CKT 472 shorted to ground inside the intake manifold. If PCM data PD05 stays 147-151°C (297-304°F) with the sensor unplugged, CKT 472 is shorted to ground.
4. IAT sensors can be damaged by a backfire in the intake manifold. If the vehicle has had more than one IAT sensor replaced, check for signs of backfire or high intake manifold temperature due to improper valve train operation.