U0603 code meaning
Lost Communication With Fuel Pressure Sensor A
Network system Generic code U06xx codes Check engine light
What U0603 means
Fuel pressure sensor A reports fuel or rail pressure, which the controller needs for injection quantity and pump control. When the sensor is digital, it transmits over a point-to-point SENT line instead of an analog voltage, and U0603 means its frames no longer arrive in usable form: wire open or shorted, signal stuck high or low, CRC errors or an internal sensor fault. No manufacturer documents this code publicly; Ford's 2023 diesel and 2024 gasoline summaries show the same pattern for other SENT sensors (U0600, U0601) with 5 s to register. CARB 1968.2 demands a dedicated code for lost communication on such inputs. P0190 covers circuit faults of an analog sensor, U0604 the second sensor. Expect a fallback pressure strategy, rough running or no start.
U0603 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0603
- Check engine light on
- Reduced power or limp mode
- Hard start, stalling or no start
Common causes of U0603
- Most likelySENT signal, 5 V supply or ground wire faulty
- PossibleFuel pressure sensor electronics failed
- PossibleLoose, corroded or fuel-contaminated connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel pressure sensor aSensor wiring
What each part of U0603 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 03 | The exact fault in that area. |
What to do next
- Note U0603 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 U0603
What does U0603 mean?
U0603 means "Lost Communication With Fuel Pressure Sensor A". Fuel pressure sensor A reports fuel or rail pressure, which the controller needs for injection quantity and pump control. It is a generic code, so it means the same on every make.
Is it safe to drive with U0603?
Drive gently and only to a workshop. With U0603 the car can go into limp mode (reduced power) to protect itself.
Will U0603 fail an emissions test?
Yes, it can. U0603 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 U0603 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2 hours of work. This is a job for a workshop.
Will U0603 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.