P2BA2Engine Coolant Pump Stuck/Stalled
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2BA2 belongs to the electric main water pump. GM uses it in a way the title does not suggest: on the 2.7-litre L3B (table 19OBDG03D) and in the 2025 table 25OBDG03B the test runs while the pump should be switched off – pump disabled or a request of 0–4 rpm for at least 3 s – and fails if the pump still reports 10 rpm or more for 8 of 10 seconds with over 11 V on board. So GM looks for a pump that keeps turning, Type B with MIL after two trips. A real blocked rotor shows up in GM's scheme as underspeed P2B85. Possible causes are faulty pump electronics, a speed signal that is not plausible, or coolant flow driving the impeller. When the pump will not stop, the engine warms up more slowly. Overspeed with air is P26CE, the command circuit P26CA.
- What you may notice
- Check engine light after two trips
- Engine takes longer to reach operating temperature
- Pump audible after the engine is switched off
- Likely causes
- LikelyPump electronics ignoring the off command
- PossibleImplausible speed feedback from the pump
- RareImpeller turned by coolant flow from another pump
- RareCommand or enable line fault keeping the pump on
- 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: €100 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.