What it means
A general circuit fault on the position feedback sensor of the EGR cooler bypass valve on bank 1. 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 bank 1 EGR cooler bypass position sensor reports how far the bypass valve has moved, allowing the controller to compare actual position with its command. This general circuit fault sets when the sensor signal or its wiring is not behaving as expected; it does not by itself identify a low or high signal condition.
Common causes
Most likely first.
- Faulty bypass position sensor
- Open or damaged sensor wiring
- Loose or corroded connector
- Bypass valve or actuator binding
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
- Save freeze-frame data and compare commanded and reported bank 1 bypass position in live data, if available, noting whether the feedback is missing or implausible.
- Inspect the bank 1 position sensor connector and harness for loose pins, corrosion, heat damage, or broken wiring.
- Check continuity and terminal contact in the sensor circuit using the wiring diagram, and inspect the circuit for unintended shorts.
- Check whether the bank 1 bypass valve or actuator binds, since restricted movement can make the position feedback disagree with the command.
- Test the bank 1 position sensor and circuit against the manufacturer's specifications, then assess the controller connection if the external circuit passes.
Common fixes
- Secure the bank 1 sensor connector and repair damaged wiring.
- Clean or replace corroded or loose connector terminals.
- Free or replace a binding bank 1 bypass valve or actuator.
- Replace the bank 1 bypass position sensor if it fails testing.
Can I keep driving?
The fault may cause reduced power, hesitation, rough idle, or knocking under load, and can increase NOx emissions. Avoid heavy loads if symptoms develop and arrange repair soon; stop if severe running problems make driving unsafe.
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.