U066F code meaning
Lost Communication With Low Pressure Fuel System Sensor
Network system Generic code U06xx codes Check engine light
What U066F means
The low-pressure side of a direct-injection fuel system runs from the tank pump to the high-pressure pump, and a sensor there lets the controller regulate the lift pump. If that sensor transmits a digital value, for example over SENT, U066F records that its messages have stopped. None of the public manufacturer documents uses the code. GM's 2025 table 25OBDG03A reads its low-side sensor, labelled fuel pressure sensor B, as a 5 V analog input at the engine controller or the pump module and fails P018C below 4 % of reference (64 failed samples in 80, Type B). Ford's 2024 summary flags its low-pressure rail sensor below 0.049 V or above 4.88 V within 8 s. Analog faults of this sensor are P2539 to P2543. Expect a MIL and possibly hard starting or hesitation under load.
U066F at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U066F
- Check engine light
- Longer cranking or hard starting
- Hesitation or power loss under heavy load
Common causes of U066F
- Most likelySignal, supply or ground wire to the low-pressure sensor damaged
- PossibleConnector at the sensor or fuel line corroded or not latched
- PossibleSensor electronics failed and no longer transmit
- Less likelyReceiving input or software of the engine or pump control module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Low pressure fuel sensorVehicle bus wiring
What each part of U066F means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6F | The exact fault in that area. |
What to do next
- Note U066F 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 U066F
What does U066F mean?
U066F means "Lost Communication With Low Pressure Fuel System Sensor". The low-pressure side of a direct-injection fuel system runs from the tank pump to the high-pressure pump, and a sensor there lets the controller regulate the lift pump. It is a generic code, so it means the same on every make.
Is it safe to drive with U066F?
Drive gently and only to a workshop. With U066F the car can go into limp mode (reduced power) to protect itself.
Will U066F fail an emissions test?
Yes, it can. U066F 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 U066F to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will U066F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.