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P0798 – Pressure Control Solenoid C Electrical (OBD2)

P0798 means "Pressure Control Solenoid C Electrical". The control unit has detected an electrical fault in the pressure control solenoid circuit – an open, a short or a resistance outside the specification.

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P0798 quick summary

Fault codeP0798
MeaningPressure Control Solenoid C Electrical
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityHigh
Can I drive?Only carefully and preferably to a workshop. Harsh or slipping shifts can damage the gearbox.
Repair cost€100 – €2,000

How pressure control solenoids work

Pressure control solenoids set the hydraulic pressure that engages the gearbox clutches; these codes cover their electrical circuits and performance.

In an automatic gearbox, the clutches and brakes are applied by hydraulic pressure. Pressure control solenoids (often labelled A, B, C) in the valve body regulate main line pressure and the pressure for individual clutches. The control unit drives them with a variable current to make shifts smooth.

Codes P0745–P0749, P0775–P0779, P0795–P0799 and P0960–P0971 report circuit faults (open, low, high, electrical), performance or stuck off, stuck on and intermittent faults.

Wrong pressure causes harsh or slipping shifts and often limp mode. Besides solenoid failures, dirty fluid and worn valve bodies are common causes.

On VAG vehicles (VW, Audi, Škoda, Seat, Cupra), VCDS and older VAG testers can show this code as the five-digit VAG code 17182 (P0798). Both numbers mean the same fault.

Symptoms of P0798

  • Harsh or slipping shifts
  • Limp mode
  • Delayed engagement into Drive or Reverse
  • Check Engine or gearbox warning
  • Shift flare

Most common causes of P0798 (most likely first)

Mechanic's Pro Tip

On many modern gearboxes the solenoids are only sold as part of the valve body or mechatronic unit – but specialist rebuilders often offer individual solenoids or reconditioned units at a much lower price.

  1. 1.Faulty pressure control solenoid (open or shorted winding)

    Most likely

  2. 2.Damaged wiring or internal gearbox harness

    Oil-soaked or chafed internal harnesses are common on automatic gearboxes.

  3. 3.Corroded or loose connector

  4. 4.Dirty or degraded gearbox fluid

  5. 5.Worn or sticking valve body

  6. 6.Transmission control unit fault

Step-by-step diagnostic guide

  1. 1

    Read codes and pressure data

    Read the transmission codes and, where available, commanded and actual pressures or solenoid currents.

  2. 2

    Measure resistance at the connector

    Measure the pressure control solenoid resistance at the control unit or gearbox connector and compare with the specification. Then check the wiring for shorts to ground.

    Multimeter: Shift and pressure solenoids typically read a few ohms up to about 15–30 Ω depending on design; "OL" means open, close to 0 Ω means shorted.

  3. 3

    Check fluid

    Check fluid level and condition and look for debris.

  4. 4

    Measure the solenoid

    Measure the solenoid resistance through the gearbox connector.

    Multimeter: Variable force/pressure solenoids often read about 3–8 Ω; check the specification.

  5. 5

    Check line pressure

    Measure line pressure with a gauge if the gearbox has a test port.

  6. 6

    Repair and adapt

    Replace the solenoid, valve body or harness as needed, change the fluid and run the adaptations.

Frequently asked questions

Can I keep driving with P0798?

Only carefully and preferably to a workshop. Harsh or slipping shifts can damage the gearbox.

How much does it cost to fix P0798?

Typical repair costs are 100 € – 2000 €, depending on the cause and the vehicle. The most common fixes are: faulty pressure control solenoid (open or shorted winding); damaged wiring or internal gearbox harness; corroded or loose connector. Always confirm the cause with the tests above before buying parts.

What does a pressure control solenoid do?

It regulates the hydraulic pressure that engages the clutches, so shifts are firm but smooth.

Can dirty fluid cause these codes?

Yes. Debris and degraded fluid can make the solenoids and valves stick.

What is the difference between P0798 and similar codes?

P0798 belongs to a group of codes for the same component that differ in the type or location of the fault: P0795 – Pressure Control Solenoid C; P0796 – Pressure Control Solenoid C Performance or Stuck off; P0797 – Pressure Control Solenoid C Stuck On; P0799 – Pressure Control Solenoid C Intermittent; P0960 – Pressure Control Solenoid A Control Circuit / Open; P0961 – Pressure Control Solenoid A Control Circuit Range/Performance. The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.