E037

ECM Code E037:

DFI Sensor Circuit:

DESCRIPTION:

The MAT sensor is a thermistor or variable resistor that varies in resistance with temperature. The MAT sensor is a two wire sensor with a reference or signal voltage coming from the ECM to sensor pin B, CKT 472 and a reference ground on pin A, CKT 476.

As the temperature of the sensor increases, sensor resistance is lower. The signal voltage from the ECM to pin B decreases as sensor temperature increases because current flows from pin B through the sensor element to pin A, sensor ground (voltage is dropped across the sensor element). High temperature means low signal voltage on CKT 472 and low temperature means high signal voltage on CKT 472. Code E037, shorted MAT sensor sets because the ECM assumes that manifold air temperature can't be 142°C or greater with a coolant of less than 105°C.

TEST CONDITIONS:

1. Codes EO14 and E015 clear.
2. Coolant sensor less than or equal to 105°C.

FAILURE CONDITIONS:

MAT sensor value greater than or equal to 142°C.

ACTION TAKEN:

1. ECM turns on "SERVICE ENGINE SOON" telltale.
2. ECM commands BCM to display "SERVICE SOON" message on CCDIC.
3. ECM turns off both air management solenoids.
4. ECM substitutes 40°C for MAT when coolant is greater than or equal to 40°C.
5. ECM uses coolant temp for MAT when coolant temp is less than or equal to 40°C.

NOTES ON FAULT TREE:

1. With a shorted sensor, ECM parameter EDO5 should read 142°C or greater, if not, then the sensor is not shorted, see note on intermittents.

2. Checking for sensor shorted or CKT 472 shorted. If ECM parameter ED05 stays at 142 to 151°C with the sensor unplugged, then the short is in CKT 472.

3. Fault is most likely at the ECM connector or ECM. Before replcing the ECM, perform the "ECM Replacement Check", CHART C-1.

4. MAT sensors can he damaged by a backfire in the intake manifold. If this vehicle has had more than one MAT sensor replaced, check for signs of backfire or high intake manifold temperatures due to improper valve train operation.

NOTE ON INTERMITTENTS:

Manipulate CKT 472 wiring, the MAT sensor and ECM connector while observing ECM parameter ED05. If the failure is induced, the manifold air temperature will jump from its normal value to the shorted reading of 142 to 151°C. If wiring and connectors check out OK, substitute a known good MAT sensor and retest.

Review the snapshot data parameters stored with this code to verify failure condition. If the failure condition is verified, check and repair intermittent wiring connection, or sensor.