P2B97Exhaust Pressure Control Valve A Position Exceeded Learning Limit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2B97 concerns the electrically driven exhaust back-pressure flap of GM's 3.0-litre Duramax diesel. After key-off the module moves the flap to its fully closed and fully open stops and stores what the SENT position sensor reports there. GM's 2025 table 25OBDG04B flags a learned value outside its window: closed below 4.8 % or above 14.7 % of 5 V, wide open below 80 % or above 96.5 %, enabled with coolant 30–150 °C and at least 9.5 V; Type A, MIL after one trip, no debounce. GM preliminary information PIP5874B for 2023 Silverado/Sierra with the 3.0 l LZ0 restricts the replacement part and asks for a borescope look at flap travel and welding slag before the valve is changed. P2B98 and P2B99 cover supply and driver faults, P0476 the general function check.
- What you may notice
- Check engine light after one drive
- Slower warm-up or reduced exhaust heating for aftertreatment
- Possibly reduced engine power
- Likely causes
- LikelyFlap travel blocked by welding slag, soot or corrosion
- PossiblePosition sensor in the actuator drifted
- PossibleActuator gear or motor worn so the stops are not reached
- RareWeak battery during the key-off learn
- 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 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.