U019F code meaning
Lost Communication With Engine Coolant Pump Control Module
Network system Generic code U01xx codes Check engine light
What U019F means
U019F means the electric engine coolant pump, which carries its own control electronics, has stopped answering. Mercedes documents it on two engines: on the M256 six-cylinder the engine controller stores U019F00 or U019F87 with a red coolant warning; LI20.10-P-075374 checks the 12 V and 48 V plugs of pump M75/11, its ground and fuse F153/2 and, if the pump touches the heat shield, insulates it or replaces the controller. On C350e and GLC350e hybrids the check engine lamp lights as well; MED40 software or a new pump fixes it. Ford SSM 46857 and 47790 (C-MAX, Fusion, MKZ hybrids) report it with an MIL from water in connectors such as C1651. Mazda warns that swapped pumps on the CX-90/CX-70 PHEV set it. U04A0 is invalid data.
U019F at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U019F
- Red coolant temperature warning
- MIL or check engine lamp on
- Engine power reduced to protect against overheating
Common causes of U019F
- Most likelyPump supply plug, 48 V connector or ground loose or dirty (Mercedes)
- PossibleWater or corrosion in front-end connectors (Ford hybrids)
- PossibleSimilar-looking pumps swapped or wrong part ordered (Mazda PHEV)
- Less likelyEngine controller software outdated (Mercedes MED40)
- Less likelyElectric coolant pump electronics faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Coolant pump moduleCAN bus
What each part of U019F means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9F | The exact fault in that area. |
What to do next
- Note U019F 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 U019F
What does U019F mean?
U019F means "Lost Communication With Engine Coolant Pump Control Module". U019F means the electric engine coolant pump, which carries its own control electronics, has stopped answering. It is a generic code, so it means the same on every make.
Is it safe to drive with U019F?
Drive gently and only to a workshop. With U019F the car can go into limp mode (reduced power) to protect itself.
Will U019F fail an emissions test?
Yes, it can. U019F 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 U019F to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U019F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.