What it means
Same as P2425 with the control line shorted to ground. 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
The EGR cooling valve controls coolant flow through the EGR cooler, which helps manage the temperature of recirculated exhaust. The engine control module monitors the valve’s control line and sets P2426 when the circuit voltage is too low, commonly because the line is shorted to ground; the valve may then fail to control coolant flow as intended.
Common causes
Most likely first.
- Control line shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
How to diagnose it
- Record freeze-frame data and check EGR and temperature live data to see when the fault occurred and whether EGR cooling appears ineffective.
- With the engine off and cool, inspect the cooling-valve harness for chafing, trapped sections, water ingress, or damaged insulation.
- Check the valve connector for corrosion, loose terminals, or pins pushed back into the connector body.
- Test the control line for a short to ground using the manufacturer’s procedure and specifications.
- If the harness and connector pass, test the valve and module circuit, then clear the code and confirm it does not return.
Common fixes
- Clean and secure corroded or loose connector terminals.
- Repair control-wire insulation or wiring shorted to ground.
- Replace a faulty EGR cooling valve if circuit tests identify it.
- Repair a verified control-module circuit fault.
Can I keep driving?
Avoid heavy loads and sustained hard acceleration if the engine knocks, hesitates, or loses power. The fault can prevent proper EGR cooling and raise emissions; stop driving if severe knocking develops.
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.