P249B EGR Cooler Bypass Position Sensor Circuit Intermittent/Erratic (Bank 2)

P249B flags short dropouts or implausible jumps in the bank 2 bypass position signal that are too brief to count as a steady low or high fault. Public manufacturer documentation for it does not exist, and even the well documented bank 1 sensor on GM's Duramax only has low, high and learning checks, without an erratic test of its own. If a controller does use P249B, the cause is rarely the sensor itself: heat cycling near the turbocharger, vibration and road splash attack terminals and harness on the second bank. A freeze-frame or a recorded drive helps to see under which load and temperature the signal breaks up. Fixing a terminal is usually enough; a new valve only follows if the fault lies inside. The bank 1 code is P2496.

Likely causes

Symptoms

• Check engine light appears now and then
• Bank 2 position value flickers in the live data

Repair estimate

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

Parts involved

Related codes

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