U0665 code meaning
Lost Communication With Fuel Rail Pressure Sensor Bank 2
Network system Generic code U06xx codes Check engine light
What U0665 means
Engines with one fuel rail per cylinder bank may give each rail its own pressure sensor, and newer ones send the reading digitally via SENT. U0665 says the controller has lost the bank 2 sensor's data. GM's 23OBDG07 and 24OBDG07 tables pair it with GM's own code U101C: path 1 trips when the signal line stays at high level, path 2 when it stays low, each after 0.5 s and within one trip. An out-of-range raw value from the same sensor is logged separately (GM P312B), and the plausibility tests of P01BF run on top. The bank 1 sensor follows the same logic with U0625 and U101B. Analog bank 2 circuit faults are P01BE to P01C2. Without a rail pressure value the controller falls back to a substitute model; reduced power and rough running are possible.
U0665 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0665
- Check engine light after one trip
- Reduced power, hesitation or rough running
- GM-specific code U101C stored alongside
Common causes of U0665
- Most likelyBank 2 sensor signal wire open or shorted to ground or voltage
- PossibleFuel-soaked, corroded or loose sensor connector
- PossibleRail pressure sensor electronics on bank 2 failed
- Less likelyEngine controller SENT input faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel rail pressure sensor bank 2Vehicle bus wiring
What each part of U0665 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 65 | The exact fault in that area. |
What to do next
- Note U0665 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 U0665
What does U0665 mean?
U0665 means "Lost Communication With Fuel Rail Pressure Sensor Bank 2". Engines with one fuel rail per cylinder bank may give each rail its own pressure sensor, and newer ones send the reading digitally via SENT. It is a generic code, so it means the same on every make.
Is it safe to drive with U0665?
Drive gently and only to a workshop. With U0665 the car can go into limp mode (reduced power) to protect itself.
Will U0665 fail an emissions test?
Yes, it can. U0665 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 U0665 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U0665 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.