P2B29 code meaning
Hybrid/EV Battery Pack Coolant Pump A Overspeed - Dry Run
Powertrain system Generic code P2Bxx codes Check engine light
What P2B29 means
A centrifugal pump that suddenly spins faster while drawing less current has lost its liquid: it is churning air. P2B29 reports exactly this for battery coolant pump A. Porsche describes the detection for the 2018 Panamera 4 E-Hybrid, where the pump watches its speed and current draw against the commanded speed and reports a dry run to the battery controller, but files it as P0C4A00 and notes it may take hundreds of miles to appear. Ford uses P2B29 itself: bulletins 20-2221 (2020 Escape HEV built up to 10 June 2020, stored in the BECM), 20-2293 and 20-2345 (hybrid Explorer, Aviator and Police Interceptor Utility) list it among MIL codes cured by reprogramming. Outside such software cases, look for leaks, low level or poor bleeding. P2B28 is the general performance code.
P2B29 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.3 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P2B29
- MIL or hybrid system warning
- Pump audibly gurgling or whining
- Battery power or charging limited
Common causes of P2B29
- Most likelyAir in the battery coolant loop after service or incomplete bleeding
- PossibleLeak in a battery cooling line lowering the level
- PossibleBattery controller software misjudging pump feedback (Ford 2020 hybrids)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hybrid battery coolant pump aBattery pack coolant loop
What each part of P2B29 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. |
| 29 | The exact fault in that area. |
What to do next
- Note P2B29 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 P2B29
What does P2B29 mean?
P2B29 means "Hybrid/EV Battery Pack Coolant Pump A Overspeed - Dry Run". A centrifugal pump that suddenly spins faster while drawing less current has lost its liquid: it is churning air. It is a generic code, so it means the same on every make.
Is it safe to drive with P2B29?
Drive gently and only to a workshop. With P2B29 the car can go into limp mode (reduced power) to protect itself.
Will P2B29 fail an emissions test?
Yes, it can. P2B29 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 P2B29 to fix?
Difficulty: medium. A typical repair takes 0.3 to 3 hours of work. This is a job for a workshop.
Will P2B29 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.