Powertrain, generic (extended)

P245B EGR Cooler Bypass Control Circuit Range/Performance (Bank 1)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P245B is set when the bank 1 bypass is electrically intact but does not reach or hold the commanded position, or when switching it has no visible thermal effect. GM's 2017 Duramax with a position-controlled DC-motor flap compares setpoint and feedback; a tracking error above 16 % in 1280 of 1600 samples, with a steady setpoint, coolant over 70 °C and outside air above minus 23 °C, sets a Type B fault, and P24A5 follows if the flap is then found stuck. Ford's 2023 diesels, the 6.7 L and the 3.0 L, run an intrusive test once per trip: the flap is moved, and if the gas temperature after the cooler changes by less than 3 °C per second, P245B is logged. Carbon on the flap shaft, a worn linkage, a weak vacuum supply or a position sensor fault are typical causes. Pure circuit faults are P245A, P245C and P245D.

Likely causes

Bypass flap or shaft sticking from carbon deposits
Bypass position feedback inaccurate
Weak vacuum supply or leaking hose on vacuum-operated bypass
Slow EGR temperature sensor after the cooler

Symptoms

  • Malfunction indicator lamp on
  • Longer warm-up or higher NOx when the bypass stays in one position

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
Time0.5–4 h

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

Parts involved

egr cooler bypass valve b1

Related codes

P245AP245CP245DP24A5P248FP2457

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