P249AEGR Cooler Bypass Position Sensor Circuit High (Bank 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P249A is logged when the bank 2 bypass position signal sits near the top of the reference voltage. Like its siblings on this bank, it is not described by any manufacturer in public documents. The bank 1 analogue P2495 is set by GM's Duramax logic once the raw value exceeds 99 % of 5 V in most of a 250-sample window, rated Type B with the lamp after two trips. A reading stuck at the top usually means the sensor has lost its ground, so the signal floats up to the supply, or that the signal wire has contact with a voltage source. A water-damaged connector can produce the same picture. Because sensor and bypass valve are often one part, a new valve is only justified after wiring and ground check out. Low on bank 2 is P2499.
- What you may notice
- Check engine light after two trips
- Bank 2 bypass position shows full scale
- Likely causes
- LikelyLost ground at the bank 2 position sensor
- PossibleSignal wire in contact with a supply line
- RareWater ingress in the sensor connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.