P2798Electric/Auxiliary Transmission Fluid Pump A Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Reduced propulsion power message on electric vehicles
- Service vehicle soon lamp or MIL
- Stop-start disabled on combustion models
- Likely causes
- LikelyControl wire chafed through to ground
- LikelyInternal defect in the pump electronics (e.g. faulty solder joints, Bolt EV/EUV)
- PossibleMoisture or corrosion bridging pins in the connector
- RareFaulty control output in the module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.