P2798 code meaning
Electric/Auxiliary Transmission Fluid Pump A Control Circuit Low
Powertrain system Generic code P27xx codes Check engine light
What P2798 means
P2798 reports the control circuit of auxiliary pump A pulled low, which in practice means a short to ground. In GM's 2025 TCM tables the controller registers less than 0.5 Ω between the signal and controller ground in 20 of 25 samples at a 100 ms rate, with battery voltage between 9 and 15 V; it is a Type B fault with the MIL after two trips. On the Chevrolet Bolt EV (2021–2023) and Bolt EUV (2022–2023), GM bulletin 21-NA-148 groups P2798 with P2797 and P0C2D: the 12-volt fluid pump on the left of the drive unit came from a batch with faulty soldering, and the pump is replaced as a unit because it cannot be repaired. Drivers get a message that propulsion power has been reduced. P2796 covers an open line, P2799 a short to voltage.
P2798 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2798
- Reduced propulsion power message on electric vehicles
- Service vehicle soon lamp or MIL
- Stop-start disabled on combustion models
Common causes of P2798
- Most likelyControl wire chafed through to ground
- Most likelyInternal defect in the pump electronics (e.g. faulty solder joints, Bolt EV/EUV)
- PossibleMoisture or corrosion bridging pins in the connector
- Less likelyFaulty control output in the module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Aux trans pump aWiring harness
What each part of P2798 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 7 | Area: transmission. |
| 98 | The exact fault in that area. |
What to do next
- Note P2798 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2798
What does P2798 mean?
P2798 means "Electric/Auxiliary Transmission Fluid Pump A Control Circuit Low". P2798 reports the control circuit of auxiliary pump A pulled low, which in practice means a short to ground. It is a generic code, so it means the same on every make.
Is it safe to drive with P2798?
Drive gently and only to a workshop. With P2798 the car can go into limp mode (reduced power) to protect itself.
Will P2798 fail an emissions test?
Yes, it can. P2798 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2798 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P2798 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.