EGR Cooler Bypass Control Stuck Closed Bank 1
The EGR cooler bypass valve on bank 1 is stuck in the closed position. EGR gas always passes through the cooler, which slows engine warm-up and can degrade cold-start emissions.
Affected components
- Egr cooler bypass valve b1
- Bypass actuator
Common causes
- High likelihood: Valve flap seized closed by soot
- Medium likelihood: Actuator linkage jammed in closed position
- Low likelihood: Carbon or debris buildup preventing free movement
Possible symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.