P2AA5EGR Cooler Bypass Control Circuit Driver Current/Temperature Too High Bank 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2AA5 comes from the H-bridge that drives the DC motor of the bank 1 EGR cooler bypass flap: the driver chip itself reports that it is getting too hot. GM's diesel summary tables carry this monitor from 2017 (17OBDG04) to 2025 (25OBDG04A) as a motor overtemperature check. The fault flag comes from the hardware layer when the bridge exceeds 170 °C; the test runs outside cranking with powertrain relay voltage above 11 V, needs 160 failures in 200 samples at a 12.5 ms task and is Type B. GM bundles it with the open and shorted circuit codes P245A, P245C and P245D as an actuator fault. A flap that binds on soot, a motor with internal damage or a partial short make the bridge work too hard. A flap stuck in one position is P24A5; bank 2 is P2AA6.
- What you may notice
- Malfunction indicator lamp on after two trips
- Bypass flap no longer driven, so warm-up EGR cooling stays at its last state
- Possible further EGR or cooler efficiency codes
- Likely causes
- LikelyBypass flap binding on soot or corrosion, motor working against resistance
- PossibleInternal fault in the bypass actuator motor
- PossiblePartial short between the motor wires
- RareOverheating or faulty H-bridge in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.