P0B39 code meaning
Motor Electronics Coolant Pump B Control Circuit Low
Powertrain system Generic code P0Bxx codes Check engine light
What P0B39 means
P0B39 sets when the control signal of motor electronics coolant pump B is lower than the controller expects, usually a short to ground on the command line or a pump input that pulls the line down. On a low-side switched or PWM line the module sees the voltage stuck low while it commands the pump off. No manufacturer documents P0B39 publicly. Pump B is in service at FCA (Compass and Renegade 4xe, performance code P0C74), and Ford stores the pump A codes P0A06 and P0A07 in the PCM of the 2020 Explorer and Aviator hybrids. CARB requires these inverter cooling outputs to be checked for circuit faults. Open and high faults are P0B38 and P0B3A; running faults use P0C74 and P2D05 ff.
P0B39 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0B39
- MIL and hybrid or coolant warning
- Pump runs permanently or not at all, depending on circuit design
- Power limitation at high load or heat
Common causes of P0B39
- Most likelyControl wire shorted to ground, often chafed at brackets
- PossiblePump electronics pulling the control input low
- PossibleCoolant or water in the pump connector
- Less likelyDriver stage in the controlling module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Motor electronics coolant pump bWiring harnessHybrid control module
What each part of P0B39 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| B | Area: hybrid propulsion. |
| 39 | The exact fault in that area. |
What to do next
- Note P0B39 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 P0B39
What does P0B39 mean?
P0B39 means "Motor Electronics Coolant Pump B Control Circuit Low". P0B39 sets when the control signal of motor electronics coolant pump B is lower than the controller expects, usually a short to ground on the command line or a pump input that pulls the line down. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B39?
Drive gently and only to a workshop. With P0B39 the car can go into limp mode (reduced power) to protect itself.
Will P0B39 fail an emissions test?
Yes, it can. P0B39 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 P0B39 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P0B39 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.