U0005 code meaning
High Speed CAN Communication Bus (+) High
What U0005 means
U0005 flags CAN-High, the (+) wire of the high-speed bus, sitting above its permitted range, generally because it touches battery voltage or a 5 V feed. Unlike a ground short this does not have to halt traffic: onsemi and NXP both found that frames still pass, but the voltage picture is distorted, noise immunity worsens and, on networks with a large capacitive load, bit timing can be violated. NXP therefore classes it as a hidden bus failure that only transceivers with diagnosis can see. The usual result is occasional message loss, intermittent warnings, or a single module that reports the fault while the car drives normally. No manufacturer documents U0005 publicly. Measuring CAN-High against ground with ignition on shows a value near supply voltage instead of about 2.5 to 3.5 V.
U0005 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0005
- Sporadic warnings, often with no lasting malfunction
- Individual messages or modules dropping out under load or in damp weather
Common causes of U0005
- Most likelyCAN-High chafed through against a battery or ignition feed
- PossibleMoisture bridging CAN-High to a supply pin in a connector
- Less likelyIncorrectly connected accessory or retrofit module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
CAN high wireModule connector
What each part of U0005 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 05 | The exact fault in that area. |
What to do next
- Note U0005 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 U0005
What does U0005 mean?
U0005 means "High Speed CAN Communication Bus (+) High". U0005 flags CAN-High, the (+) wire of the high-speed bus, sitting above its permitted range, generally because it touches battery voltage or a 5 V feed. It is a generic code, so it means the same on every make.
Is it safe to drive with U0005?
U0005 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0005 fail an emissions test?
U0005 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 U0005 to fix?
Difficulty: hard. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will U0005 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.