P249BEGR Cooler Bypass Position Sensor Circuit Intermittent/Erratic (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
- P249B flags short dropouts or implausible jumps in the bank 2 bypass position signal that are too brief to count as a steady low or high fault. Public manufacturer documentation for it does not exist, and even the well documented bank 1 sensor on GM's Duramax only has low, high and learning checks, without an erratic test of its own. If a controller does use P249B, the cause is rarely the sensor itself: heat cycling near the turbocharger, vibration and road splash attack terminals and harness on the second bank. A freeze-frame or a recorded drive helps to see under which load and temperature the signal breaks up. Fixing a terminal is usually enough; a new valve only follows if the fault lies inside. The bank 1 code is P2496.
- What you may notice
- Check engine light appears now and then
- Bank 2 position value flickers in the live data
- Likely causes
- LikelyFretting or loose terminal in the bank 2 sensor plug
- PossibleHarness brittle from heat near the turbocharger
- RareIntermittent fault inside the sensor
- 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: €20 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.