P2491EGR Cooler Bypass Control 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
- P2491 reports excess voltage or excess current in the drive circuit feeding the bypass actuator on bank 2, the classic sign of a short to supply or of a winding whose resistance has collapsed. It is the bank 2 sibling of P245D, and no maker publishes its own description of it. GM's 2017 tables show how a bank 1 DC-motor flap is protected: if H-bridge current climbs past 8 A in 160 of 200 samples, the output is flagged and the code is rated Type B. Many controllers switch off the affected driver to protect it, so the flap falls back to its spring-loaded rest position. A blown fuse feeding the actuator or a damaged controller output can accompany the code. Open circuit is P248E, ground short P2490.
- What you may notice
- Check engine light on
- Bypass flap on bank 2 rests in its default position
- Likely causes
- LikelyControl wire touching a battery or ignition feed
- PossibleActuator winding with too low resistance or seized motor
- RareController software reporting a false actuator fault
- 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: €0 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.