P1391 ACURA, BUICK, CADILLAC, CHEVROLET, GMC, HONDA, ISUZU, SUZUKI: WHEEL SPEED SENSOR 1-G-SENSOR CIRCUIT PERFORMANCE
POST UPDATED IN January, 2023
P1391 ACURA, BUICK, CADILLAC, CHEVROLET, GMC, HONDA, ISUZU, SUZUKI: WHEEL SPEED SENSOR 1-G-SENSOR CIRCUIT PERFORMANCE
The G-Sensor (Road Sensor) is a vertical low acceleration sensor with gravity (G) detection. When vertical acceleration that is caused by potholes is detected, the ECM (Engine Control Module) can take action and determine if the changes in crankshaft speed are due to engine misfiring, or if they are induced by the transmission line instead. If the G-Sensor notices a hard road condition, the ECM‘s misfire detection diagnosis will be activated.
When the G-Sensor is at rest, the output of the sensor should be between 2.35 to 3.65 volts (+1G) and during a difficult road condition, the voltage output may vary between 0.5v (-1G) and 4.5v (+3G).
If during the operation of the vehicle’s engine, voltage changes are detected in the G-Sensor, which are not within the parameters already set by the manufacturer, the diagnostic code P1391 OBDII will be stored. However, it should be noted that the G-Sensor shares the 5-volt reference of the ECM and the ground terminals with the A/C Pressure Sensor. Therefore, if the A/C Pressure Sensor or its wiring is damaged, the code P1391 can be set.
The reasons why the fault code P1391 OBD2 is set are
The steps to follow to solve the DTC code P1391 OBDII are