What it means
The output driver for the EGR cooler bypass actuator on bank 1 reports current or junction temperature above its protection threshold. Stalled actuator or short to ground.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The EGR cooler bypass actuator on bank 1 directs exhaust around or through the cooler as needed. Its output driver monitors electrical current and its own temperature; P2AA5 sets when current or driver temperature exceeds the protection threshold, which can happen if the actuator is jammed or its control wire is grounded.
Common causes
Most likely first.
- Bypass actuator mechanically jammed
- Control wire shorted to ground
Symptoms
- Check engine light on
- Possible reduced power
How to diagnose it
- Record freeze-frame data and check bank 1 bypass command and related EGR codes to see when the driver fault occurs.
- Locate the bank 1 EGR cooler bypass actuator and inspect its connector and harness for damage or a wire contacting ground.
- Check the bank 1 bypass mechanism for binding or a jam that could overload the actuator.
- Test the bank 1 actuator control circuit for a short to ground using the manufacturer's procedure.
- If the wiring is sound, test the bank 1 actuator and driver operation according to the manufacturer's diagnostic procedure.
Common fixes
- Repair the bank 1 control wire if it is shorted to ground.
- Free or repair the bank 1 bypass mechanism if it is mechanically jammed.
- Replace the bank 1 bypass actuator if it is internally drawing excessive current.
- Clear the code and confirm the bank 1 actuator operates without overloading its driver.
Can I keep driving?
If the engine runs normally, limit hard use and arrange diagnosis; reduced power may occur as EGR control is affected. Stop if the engine overheats or develops severe drivability problems.
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.