The hydraulic pressure sensor circuit relays information about the available hydraulic pressure inside the transmission to the ECU. This allows the vehicle’s computer to adjust the transmission according to the engine’s current load and driving conditions. If the ECU detects a low voltage signal from the pressure sensor circuit of this transmission line, a DTC P0934 will be set.
How severe is the code?
Diagnostic code P0934 is very serious, as it means the ECU does not know how much hydraulic pressure is built up inside the transmission. This can lead to a number of driving issues, including unusual shifting and locking in higher gears.
Symptoms
Symptoms of a P0934 include:
- Harsh shifting at low RPM
- Slow shifting as RPM increases
- Weaker acceleration power than usual (because the ECU tells the transmission to start in a higher gear)
- Engine runs at higher RPM at speed (if the ECU has told the transmission not to shift to higher gears)
Causes
- Damage to wiring or connectors
- Faulty fuses
- Defective transmission pressure sensor
- ECU/TCM issues
How to diagnose the code?
The first step in diagnosing an OBDII P0934 fault code is to check all cables, grounds, and connectors along the transmission pressure sensor circuit. All associated fuses or relays should also be tested. If no issues are detected, the hydraulic pressure sensor itself will need to be tested. In rare cases, the ECU/TCM may actually be to blame.