Powertrain, generic (extended)

P2490 EGR Cooler Bypass Control Circuit Low (Bank 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2490 means the drive line of the bank 2 cooler bypass actuator sits too close to ground potential, typically a grounded wire between controller and actuator. It mirrors P245C on bank 1. No manufacturer documents P2490 publicly. GM's 2017 diesel tables give an idea of the bank 1 test: the vacuum-switched bypass is failed when the resistance to ground falls below 0.5 Ohm in 24 of 30 samples. Depending on the wiring, a grounded control line can keep the actuator permanently energised or permanently released, so bank 2 either always bypasses or always cools. Look for chafed insulation near the exhaust manifolds and turbocharger, harness clips lost after repairs and water in the connector. An open is P248E, a short toward the supply P2491.

Likely causes

Drive wire rubbed through and touching engine ground
Water or corrosion in the bank 2 actuator connector
Internal short in the actuator

Symptoms

  • Check engine light on
  • Bypass on bank 2 stuck in one mode, possibly followed by cooler efficiency codes

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–600
Time0.5–3 h

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

Parts involved

egr cooler bypass valve b2

Related codes

P245CP248EP2491

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