Powertrain, generic (extended)

P249A EGR Cooler Bypass Position Sensor Circuit High (Bank 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Lost ground at the bank 2 position sensor
Signal wire in contact with a supply line
Water ingress in the sensor connector

Symptoms

  • Check engine light after two trips
  • Bank 2 bypass position shows full scale

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–800
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

egr cooler bypass position sensor b2

Related codes

P2495P2497P2498P2499

References: law.cornell.edu, gsi.ext.gm.com.