EGR Cooler Bypass Control Circuit/Open
What does DURAMAX-P245A mean?
The DURAMAX-P245A (Duramax) diesel fault code means: EGR Cooler Bypass Control Circuit/Open. This is a moderate severity code.
Common Symptoms
- Check Engine Light illuminated
- Reduced engine performance
- Limp mode or 'Service Engine' message
- Rough idle or stalling (sensor-related)
- Hard shift or slip (transmission codes)
Probable Causes (Ranked by Likelihood)
- EGR bypass valve actuator open circuit Very Likely
- Wiring harness damage or connector corrosion Likely
- Sensor end-of-life (high mileage engines) Possible
- Control module internal fault Less Likely
Step-by-Step Diagnostic Procedure
Connect scan tool and capture freeze frame data showing when fault occurred
Verify battery voltage and all PCM grounds are clean and tight
Back-probe the suspect sensor / circuit with a DMM and compare to spec
Inspect wiring harness for abrasion, chafing, or rodent damage
After repair, clear code and drive a complete drive cycle to confirm fix
Frequently Asked Questions
What is P245A on a Duramax?
Duramax code P245A (EGR Cooler Bypass Control Circuit/Open) is a moderate-severity diagnostic trouble code triggered by the engine control module when it detects a problem in the associated system. A bad 5V reference (P0642/P0643) will cascade into multiple unrelated sensor codes — always diagnose reference voltage first.
Is a Duramax P245A safe to drive?
Depends on severity — sensor codes usually drivable; PCM/transmission codes should be repaired before continued use.
How much does it cost to fix P245A on a Duramax?
Component repairs typically $100-$500. Control module replacement $800-$2,500.
P245A on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: