P2E46Hybrid/EV Electronics Coolant Pump B Overspeed - Dry Run
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2E46 is the dry-run report of electronics coolant pump B: faster than commanded at lower current, the signature of air at the impeller. Porsche describes such self-monitoring on the traction-battery pump of the 2018 Panamera plug-in hybrid (code P0C4A00 there). On Mercedes 167-series SUVs with the M177 V8 and 48 V, trapped air forces the 15 W low-temperature pump into a protective dry-run state and sets pump A's P2B2A7A with a yellow coolant warning; Mercedes prescribes vacuum filling and repeated venting. For BAE hybrid buses the pump maker EMP warned that filling with the pump at only 20 % speed leaves air at the inlet and ruins the shaft seals. No manufacturer publicly documents P2E46. Bleed the loop and find the leak first. Plain overspeed is P2E48, pump A's dry-run code P2B2A.
- What you may notice
- Coolant warning message and MIL
- Pump starts briefly, then stops again
- Gurgling noise or falling level in the electronics reservoir
- Likely causes
- LikelyLow coolant level from a leaking hose, joint or component
- LikelyAir left in the loop after service without vacuum fill
- RarePump B damaged by earlier dry running
- 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: €80 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.