What the P0904 code means?
In most vehicles manufactured today, the TCM and ECM use various sensors to monitor and control the
performance of the transmission. One of those sensors is the gate select position sensor, which tells the
TCM and ECM what gear position the driver has put the vehicle in. These sensors are also used to monitor
brake slippage and to detect clutch application in a manual vehicle. If the ECM is not receiving the correct
signal from this sensor, it will register the P0904 code.
What causes the P0904 code?
1. Faulty Gate Select Position Actuator
2. Gate Select Position Actuator harness is open or shorted
3. Gate Select Position Actuator circuit poor electrical connection
What are the symptoms of the P0904 code?
Engine Light ON
Common mistakes when diagnosing the P0904 code:
When diagnosing the underlying cause of the P0904 code, the most common mistake is forgetting to
disconnect the PCM and the cruise control module when testing circuit resistance. It is also important to
clear the code and do a road test after each potential solution is attempted. If the most common repairs do
not stop the Check Engine light from reappearing, it can be a sign of an intermittent issue that requires an
in-depth inspection and servicing.
What repairs can fix the P0904 code?
Realign any sensors that were not in the correct position.
Replace or repair any electrical components that were not operating correctly.
Replace a faulty sensor.