U043F code meaning
Invalid Data Received From Vacuum Sensor B
What U043F means
U043F is the counterpart for vacuum sensor B, used where a second vacuum signal exists, for example a redundant booster sensor or one watching a separate reservoir. A receiver records it when B's digital vacuum value arrives invalid. Comparing with U043E narrows the search: B alone points at that sensor or its wiring branch, both together at a shared supply, the bus or a genuine vacuum shortage. No manufacturer documents U043F publicly and no thresholds are known; in GM's analogue designs a booster sensor fault shows up as a P-code such as P0557 instead. Without a trustworthy second value the receiver loses its cross-check between the two sensors, so a brake assist warning and disabled vacuum-dependent functions are the likely consequence. U013E is lost contact.
U043F at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U043F
- Brake assist or vacuum system warning
- Start-stop or other vacuum-dependent functions inactive
Common causes of U043F
- PossibleFaulty vacuum sensor B or its electronics
- PossibleDamaged wiring branch or connector to sensor B
- Less likelyActual vacuum leak making both sensors disagree
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Vacuum sensor b
What each part of U043F means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3F | The exact fault in that area. |
What to do next
- Note U043F 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 U043F
What does U043F mean?
U043F means "Invalid Data Received From Vacuum Sensor B". U043F is the counterpart for vacuum sensor B, used where a second vacuum signal exists, for example a redundant booster sensor or one watching a separate reservoir. It is a generic code, so it means the same on every make.
Is it safe to drive with U043F?
U043F does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U043F fail an emissions test?
U043F 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 U043F to fix?
Difficulty: medium. A typical repair takes 0.3 to 1.5 hours of work. This is a job for a workshop.
Will U043F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.