What it means
Same as P23E5 with valve C stuck closed - no EGR through this stage; NOx emissions rise. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
EGR valve C meters exhaust into the intake through the C stage or loop to help limit combustion temperature. The module detects that the valve remains closed when it should open, preventing EGR flow through this stage and potentially raising NOx emissions.
Common causes
Most likely first.
- Valve stuck closed
- Carbon or debris buildup preventing free movement
- Component wear with age - mechanical play
Symptoms
- Check engine light
- Possible rough idle, hesitation, or reduced power
- Increased emissions or failed emissions test
How to diagnose it
- Save freeze-frame data and compare commanded with reported EGR valve C position to confirm when the valve fails to open.
- Inspect the valve C connector and wiring for damage or a loose connection that could prevent actuator movement.
- Check the EGR C valve and its passage for soot or debris that may physically block opening.
- Inspect the C-loop cooler and connecting passages for restrictions that could prevent the expected flow.
- Test valve C actuator operation and position feedback against the manufacturer's specification.
Common fixes
- Clean carbon or debris that is preventing the EGR C valve from opening.
- Repair a loose connector or damaged valve C wiring.
- Clear a confirmed restriction in the C-loop passage or cooler.
- Replace the EGR valve C if its mechanism or actuator cannot open it as commanded.
Can I keep driving?
If the engine runs normally, limited driving may be possible, but avoid sustained heavy loads until the fault is diagnosed. No EGR flow through stage C can increase NOx emissions and may lead to reduced performance or an emissions test failure.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.