P2E79Hybrid/EV Electronics Coolant Pump C Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- P2E79 is the functional verdict on a third pump in the coolant loop of the traction electronics: command and wiring look healthy, yet the pump does not move coolant the way the controller expects. No manufacturer documents P2E79 or says which pump it calls C. GM has published two strategies for its electronics pump: the 2016 ELR sets P0CEA when the spread between power-electronics coolant temperature and charger temperature grows too large once the pump has been on for over 300 s (32 failures in 40, Type B), and the 2019 tables smooth the difference of commanded versus fed-back pump speed (P19FC). A GM patent adds a comparison of measured with expected pump current. Trapped air, blocked passages, a worn impeller or software can be behind it; Stellantis cured a comparable pump B code (P0C74) by a reflash.
- What you may notice
- Hybrid or EV system warning lamp, possibly MIL
- Drive power or charging rate limited because electronics run warm
- Gurgling or whirring noise from the electronics coolant loop
- Likely causes
- LikelyAir trapped in the electronics coolant loop after service or a leak
- PossiblePump C worn or impeller fouled, delivering too little flow
- PossibleKinked hose or clogged cooler passages in the loop
- RareControl software misjudging pump function (update available)
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.