P2DE9Cold Start Engine Coolant Pump Underspeed
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Engines with an electric main water pump run it at a tightly metered speed after a cold start so the block heats quickly. P2DE9 flags that during this phase the pump turns too slowly. GM's 2025 ECM tables (25OBDG03B) filter the gap between requested and reported pump speed and fail the check when it exceeds 200 rpm for 8 of 10 seconds, with low-flow coolant mode and catalyst warm-up active, the request steady within 50 rpm for at least 3 s, and inlet coolant at −40 °C or warmer; two calibrated limits exist because the reachable speed depends on system voltage. Type B, MIL after two trips. Outside the warm-up phase the same fault is P2B85; pump faster than requested during cold start is P2E82. CARB demands such separate cold-start codes and a monitoring plan for electric water pumps.
- What you may notice
- Check engine light on after two trips
- Uneven warm-up, local hot spots possible
- Often no noticeable symptom
- Likely causes
- LikelyWorn pump bearing or debris at the impeller slowing the rotor
- PossibleLow supply voltage at the pump (battery, ground, connector)
- PossibleFaulty pump electronics or speed feedback
- RareWrong or aged coolant, very thick when cold
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · 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.