P2491 code meaning
EGR Cooler Bypass Control Circuit High (Bank 2)
Powertrain system Generic code P24xx codes Check engine light
What P2491 means
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.
P2491 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P2491
- Check engine light on
- Bypass flap on bank 2 rests in its default position
Common causes of P2491
- Most likelyControl wire touching a battery or ignition feed
- PossibleActuator winding with too low resistance or seized motor
- Less likelyController software reporting a false actuator fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR cooler bypass valve b2
What each part of P2491 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 91 | The exact fault in that area. |
What to do next
- Note P2491 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2491
What does P2491 mean?
P2491 means "EGR Cooler Bypass Control Circuit High (Bank 2)". 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 a generic code, so it means the same on every make.
Is it safe to drive with P2491?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2491 fail an emissions test?
Yes, it can. P2491 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2491 to fix?
Difficulty: medium. A typical repair takes 0.3 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2491 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.