P2B58 code meaning
Engine Coolant Flow Control Valve Motor Current High
Powertrain system Generic code P2Bxx codes Check engine light
What P2B58 means
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.
P2B58 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1 to 10 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2B58
- MIL on after the second drive with the fault
- Slow warm-up or weak cabin heat
- Fans may run more often as a precaution
Common causes of P2B58
- Most 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)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Engine coolant flow control valveWiring harnessECM
What each part of P2B58 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| B | Area: hybrid propulsion. |
| 58 | The exact fault in that area. |
What to do next
- Note P2B58 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2B58
What does P2B58 mean?
P2B58 means "Engine Coolant Flow Control Valve Motor Current High". P2B58 reports that the electric motor driving the engine coolant flow control valve draws too much current. It is a generic code, so it means the same on every make.
Is it safe to drive with P2B58?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2B58 fail an emissions test?
Yes, it can. P2B58 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2B58 to fix?
Difficulty: hard. A typical repair takes 1 to 10 hours of work. This is a job for a workshop.
Will P2B58 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.