P0945: Hydraulic Pump Relay Circuit/Open OBD-II Trouble Code

The P0945 DTC gets triggered when the ECU detects an electrical problem on the hydraulic pump relay circuit. Often called the transmission pump, this is one of the most important transmission parts in your gearbox. So this OBDII trouble code should be diagnosed immediately.

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What Transmission Do I Have?

How Serious is the Code?

The P0945 diagnostic trouble code is extremely serious, because the transmission pump is what creates the hydraulic pressure that ultimately turns your wheels. If there is a problem with the transmission pump relay, you can experience a number of drivability issues, while causing significant or catastrophic transmission damage.

Symptoms

Symptoms of a P0945 include:

  • Unusually harsh shifts
  • Transmission slips between gears
  • Failed gear changes

Causes

  • Low or dirty transmission fluid
  • Damaged wiring or connectors
  • Failed hydraulic pump relay
  • ECU or TCM issues

How to Diagnose the Code?

The first step to diagnosing a P0945 OBDII trouble code, is to check the level and condition of the transmission fluid. Next, the technician should look for any damage wiring or corroded connectors between the relay panel and the transmission. The hydraulic pump relay/transmission pump relay will also need to be tested.

What Repairs Will Fix P0945?

  • Change transmission fluid/filter
  • Repair or replace damaged wiring and/or connectors
  • Replace hydraulic pump relay
  • Reprogram or replace ECU/TCM

Related Codes

N/A

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?