P2B58Engine Coolant Flow Control Valve Motor Current High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2B58 reports that the electric motor driving the engine coolant flow control valve draws too much current. GM documents the check for its 3.0-litre inline-six Duramax diesel: in the 2025 table 25OBDG04B the driver stage flags a current above 5.5 A, and 80 failures in 100 samples taken every 12.5 ms set a Type B fault, so the MIL follows on the second trip. Enabling needs more than 11 V on the powertrain relay and an engine that is not cranking. A seized rotary valve, debris in the housing or a motor with shorted windings are typical reasons. GM bulletin 21-NA-149 lists P2B58 for LM2 trucks with a chafed engine harness. Heating and warm-up may suffer while the valve is stuck.
- What you may notice
- MIL on after the second drive with the fault
- Slow warm-up or weak cabin heat
- Fans may run more often as a precaution
- Likely causes
- LikelyRotary valve stiff or seized from deposits or debris in the housing
- PossibleValve motor with shorted turns
- PossibleChafed engine harness on GM LM2 (bulletin 21-NA-149)
- 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 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.