What it means
EGR throttle A drive line stuck low — short 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 throttle controls intake airflow so the engine can meter exhaust gas recirculation. The control module monitors drive circuit A for an abnormally low electrical level; a short to ground can keep the actuator from following commands and reduce EGR flow.
Common causes
Most likely first.
- Control wire shorted to ground
- Chafed or damaged wiring
- Corroded or bridged connector pins
- Faulty EGR throttle actuator or driver
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 compare commanded EGR throttle position with available position and EGR data to see when circuit A faulted.
- Inspect the EGR throttle A connector and harness for chafing, corrosion, bent pins, or contact with grounded metal.
- Check circuit A for continuity to ground with the circuit isolated as specified by the manufacturer; an unintended ground indicates a short.
- Test the actuator and driver circuit using the manufacturer's procedure to separate a wiring short from an internal actuator or driver fault.
- After repair, clear the code and confirm circuit A and EGR operation during a suitable drive cycle.
Common fixes
- Repair chafed or pinched wiring that is grounding EGR throttle circuit A.
- Clean or repair corroded, damaged, or bridged connector pins.
- Replace a failed EGR throttle actuator if its circuit tests identify an internal fault.
- Repair the control module driver only if wiring and actuator checks pass and the manufacturer's tests confirm driver failure.
Can I keep driving?
You can usually drive gently if the engine runs smoothly, but avoid heavy loads if it pings, hesitates, or loses power. Incorrect EGR flow can increase NOx emissions and worsen drivability.
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.