U02BA code meaning
Lost Communication With Hybrid/EV Electronics Coolant Pump B
Network system Generic code U02xx codes Check engine light
What U02BA means
Hybrid and electric cars cool their power electronics, such as inverter, DC/DC converter and on-board charger, with electric pumps that hang on a LIN line and report their state to a thermal or vehicle controller. U02BA means pump B of that loop no longer answers. No manufacturer documents U02BA publicly or says which pump bears the letter B. Stellantis shows the layout on the 2024-2025 Dodge Charger and Jeep Wagoneer S: three identical pumps, each with its own software and its own LIN bus to the EVCU; without a master message a pump falls into an emergency mode at full speed and can drain the 12 V battery (STAR S2508000056). GM's 2011 Volt wired pump A directly and rated its circuit fault P0CE9 as Type B. With pump B silent the electronics run hotter and drive power may be cut.
U02BA at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of U02BA
- Warning for the hybrid/electric drive system, MIL possible
- Reduced drive or charging power when the electronics warm up
- Pump running constantly or not at all, 12 V battery drained
Common causes of U02BA
- Most likelyLoose or corroded pump connector, open or shorted LIN wire
- PossiblePump power supply or ground missing (fuse, relay, ground point)
- PossiblePump electronics failed or pump seized
- Less likelyPump of another position fitted or controller software outdated
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv electronics coolant pump bVehicle bus wiring
What each part of U02BA means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| BA | The exact fault in that area. |
What to do next
- Note U02BA 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 U02BA
What does U02BA mean?
U02BA means "Lost Communication With Hybrid/EV Electronics Coolant Pump B". Hybrid and electric cars cool their power electronics, such as inverter, DC/DC converter and on-board charger, with electric pumps that hang on a LIN line and report their state to a thermal or vehicle controller. It is a generic code, so it means the same on every make.
Is it safe to drive with U02BA?
Drive gently and only to a workshop. With U02BA the car can go into limp mode (reduced power) to protect itself.
Will U02BA fail an emissions test?
Yes, it can. U02BA 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 U02BA to fix?
Difficulty: hard. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U02BA 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.