OBD-II code · Powertrain (generic, extended)
P249B EGR Cooler Bypass Position Sensor Circuit Intermittent or Erratic Bank 2
Same as P2496 on bank 2. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
Is it safe to drive with P249B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyIntermittent contact at connector
- Less likelyConnector with intermittent contact under vibration
- Less likelyHarness routed against vibrating component
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.8–2 h
- Emissions test
- Likely to fail
- Parts involved
- Egr Cooler Bypass Position Sensor B2
Related codes
- P2496EGR Cooler Bypass Position Sensor Circuit Intermittent or Erratic Bank 1
- P2498EGR Cooler Bypass Position Sensor Range or Performance Bank 2
- P2499EGR Cooler Bypass Position Sensor Circuit Low Bank 2
- P249AEGR Cooler Bypass Position Sensor Circuit High Bank 2
- P249CExcessive Time To Enter Closed Loop Reductant Injection Control
- P249DClosed Loop Reductant Injection Control At Limit Flow Too Low
- P249EClosed Loop Reductant Injection Control At Limit Flow Too High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.