P249A code meaning
EGR Cooler Bypass Position Sensor Circuit High (Bank 2)
Powertrain system Generic code P24xx codes Check engine light
What P249A means
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.
P249A at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P249A
- Check engine light after two trips
- Bank 2 bypass position shows full scale
Common causes of P249A
- Most likelyLost ground at the bank 2 position sensor
- PossibleSignal wire in contact with a supply line
- Less likelyWater ingress in the sensor connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR cooler bypass position sensor b2
What each part of P249A 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). |
| 9A | The exact fault in that area. |
What to do next
- Note P249A 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 P249A
What does P249A mean?
P249A means "EGR Cooler Bypass Position Sensor Circuit High (Bank 2)". P249A is logged when the bank 2 bypass position signal sits near the top of the reference voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P249A?
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 P249A fail an emissions test?
Yes, it can. P249A 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 P249A to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P249A 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.