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.
Medium severity. Can I keep driving?Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
Symptoms
- Reduced propulsion power message on electric vehicles
- Service vehicle soon lamp or MIL
- Stop-start disabled on combustion models
Most likely causes
- Control wire chafed through to ground
- Internal defect in the pump electronics (e.g. faulty solder joints, Bolt EV/EUV)
- Moisture or corrosion bridging pins in the connector
- Faulty control output in the module
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It can trigger limp mode.
- It affects emissions.
What each character of P2798 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 7: Transmission
- 98: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2798?
Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
What causes code P2798?
The most common causes are: control wire chafed through to ground; internal defect in the pump electronics (e.g. faulty solder joints, Bolt EV/EUV); moisture or corrosion bridging pins in the connector.
Related codes
- P2796Electric/Auxiliary Transmission Fluid Pump A Control Circuit/Open
- P2799Electric/Auxiliary Transmission Fluid Pump A Control Circuit High
- P2797Electric/Auxiliary Transmission Fluid Pump A Performance/Stuck Off
- P0C2DElectric/Auxiliary Transmission Fluid Pump Control Module Feedback Signal Low
- P27A4Electric/Auxiliary Transmission Fluid Pump B Control Circuit Low
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.