Powertrain, generic (extended)

P24A5 EGR Cooler Bypass Control Stuck/Open (Bank 1)

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P24A5 means the bank 1 cooler bypass is mechanically stuck, and makers read that in both directions. GM's 2017 Duramax DC-motor flap is judged stuck in bypass if the position is still above 15 % after P245B; the 2018 vacuum version is moved between both modes and fails when the gas temperature after the cooler barely reacts, both Type B. Ford's 2013 and 2015 diesel summaries use it as an overcooling test on the 6.7 L and 3.2 L: with the flap commanded to cooling, gas after the cooler stays below a coolant-based limit for 12 seconds, a sign the flap sits in cooling. Ford traced early cases on 2016–17 Transit 3.2 L vans (TSB 17-0009) to a wrong EGR cooler; Ram reflashed 2014 6.7 L Cummins trucks to cut needless lamps (18-053-14). Bank 2 is P24A6.

Likely causes

Bypass flap seized by soot and carbon deposits

Actuator, linkage or vacuum supply no longer moving the flap

Incorrect EGR cooler fitted at the factory

Engine software that sets the fault too readily

Symptoms

Check engine light on
Slow warm-up or more soot when the flap is stuck in cooling
Higher NOx and EGR gas temperatures when stuck in bypass

Repair estimate

DifficultyHardWorkshop job

Parts and labour€100–1,800

Time1–6 h

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

Parts involved

egr cooler bypass valve b1

Related codes

P24A6 P245B P2457 P245A P2493

References: gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com, fordservicecontent.com.