U0628 code meaning
Lost Communication With A/C Refrigerant Pressure Sensor B
What U0628 means
A second pressure transducer appears mainly in heat pumps and CO2 (R744) systems, where both the low and the high side are measured to control efficiency and detect leaks; the Sensata R744 presentation lists heat-pump control and leak diagnosis among those uses. U0628 means that the digital pressure value from sensor B no longer reaches its controller. If sensor A still reports while B is silent, the fault is likely in B's own branch, plug or electronics rather than in the controller. No manufacturer documents U0628 publicly. Losing the second pressure value usually ends heat-pump operation or forces a conservative compressor mode. Hardwired faults of the same sensor show as P2515 to P2518 or P05E2; disagreement between A and B is P2CD4.
U0628 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0628
- Heat pump does not heat, cabin heating relies on the auxiliary heater
- Weak or no A/C cooling
- A/C or thermal system warning message
Common causes of U0628
- Most likelyDamaged LIN, supply or ground wire in the branch to sensor B
- PossibleWet, corroded or loose connector at sensor B
- PossibleSensor B electronics failed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ac refrigerant pressure sensor bVehicle bus wiring
What each part of U0628 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 28 | The exact fault in that area. |
What to do next
- Note U0628 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 U0628
What does U0628 mean?
U0628 means "Lost Communication With A/C Refrigerant Pressure Sensor B". A second pressure transducer appears mainly in heat pumps and CO2 (R744) systems, where both the low and the high side are measured to control efficiency and detect leaks; the Sensata R744 presentation lists heat-pump control and leak diagnosis among those uses. It is a generic code, so it means the same on every make.
Is it safe to drive with U0628?
U0628 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0628 fail an emissions test?
U0628 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U0628 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U0628 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.