Powertrain, generic (extended)

P2491 EGR Cooler Bypass Control Circuit High (Bank 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Control wire touching a battery or ignition feed
Actuator winding with too low resistance or seized motor
Controller software reporting a false actuator fault

Symptoms

  • Check engine light on
  • Bypass flap on bank 2 rests in its default position

Repair estimate

DifficultyMediumDIY possible
Parts and labour€0–700
Time0.3–3 h

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

Parts involved

egr cooler bypass valve b2

Related codes

P245DP248EP2490

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