P1115 General Temperature Rationality

P1115 code - This diagnostic runs one time during an ignition cycle when Battery voltage is greater than 7.5 volts, engine off time is greater than 480 minutes, Intake manifold mass flow is greater than 20 grams/sec, Ambient temperature is greater than -64°C (-83°F), vehicle driven over 30 mph for 30 seconds.

P1115


Set condition once the vehicle is soaked for a calibrated engine off time and then driven over calibrated speed and load conditions for a calibrated time, the PCM compares the ambient air, engine coolant and intake air temperature sensor values. If the values of all the three sensors are more than 15°C apart, the general temperature sensor rationality test fails.

Default actions:
- The MIL light illuminate
- If the vehicle is equipped with the stop/start feature, the system will be disabled when this DTC is active.

Possible causes P1115 code

- Excessive resistance in the sensor signal circuit
- Excessive resistance in the sensor ground circuit
- Sensor signal circuit shorted to ground
- Sensor signal circuit shorted to voltage
- Sensor signal circuit shorted to the sensor ground circuit
- Temperature sensor
- Powertrain Control Module (PCM)

Diagnostic test P1115 code

Step 1. Temperature sensor comparison
All ECT, Intake Air and Ambient Air Temperature sensor codes must be diagnosed and repaired before continuing. In cold waeter, this DTC could be set by a high powered block heater and no repair would be required.
Turn the ignition off. If possible, allow the vehicle to sit with ignition off for more than 480 minutes in an environment where the temperature is consistant and above -64°C (-83°F). Turn the ignition on, with the scan tool read the ECT, Ambient Air Temperature and Intake Air Temperature sensor values.

Are the temperature readings within 15°C (59°F) of each other?

Yes, perform the PCM intermittent condition.
No, go to step 2.

Step 2. Temperature sensor
Disconnect the suspected sensor, with the scan tool read the voltage of the suspected sensor. Connect a jumper between the sensor signal circuit and the sensor ground of the suspected sensor.

Did the voltage reading start at 4.8 to 5.0 volts and decrease to 0 volts when the jumper was installed?

Yes, verify that there is good pin to terminal contact in the sensor and control module connectors. If no problems are found, replace the appropriate temperature sensor.
No, go to step 3. Remove the jumper before continuing.

Step 3. Check for high resistance in the temperature sensor signal circuit
Turn the ignition off, disconnect the appropriate PCM harness connector. Disconnect the appropriate BCM harness connector, measure the resistance of the suspect sensor signal circuit between the sensor harness connector and the appropriate terminal of PCM harness connector or BCM harness connector.

Is the resistance below 3.0 Ohms?

Yes, go to 4.
No, repair the excessive in the temperature sensor signal circuit.

Step 4. Check for high resistance in the sensor ground circuit
Measure the resistance of the sensor ground circuit between the sensor harness connector and appropriate terminal of PCM harness connector or BCM harness connector.

Is the resistance below 3.0 Ohms?

Yes, go to step 5.
No, repair the sensor ground circuit for an open or high resistance.

Step 5. Check the sensor signal circuit for a short to ground
Check for continuity between ground and the sensor signal circuit at the sensor harness connector.

Is there continuity between ground and the sensor signal circuit?

Yes, repair the sensor signal circuit for a short to ground.
No, go to step 6.

Step 6. Check for the sensor circuit shorted to the sensor ground circuit
Check for continuity between the sensor ground and the sensor signal circuit at the sensor harness connector.

Is there continuity between the sensor ground and the sensor signal circuit?

Yes, repair the short between the sensor ground circuit and the sensor signal circuit.
No, go to step 7.

Step 7. Sensor signal circuit shorted to voltage
Turn the ignition on, measure the voltage on the sensor signal circuit at the sensor harness connector.

Is there any voltage present?

Yes, repair the sensor signal circuit for a short to voltage.
No, go to step 8.

Step 8. Check related PCM and component connections

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