U0005 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. 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.

Likely causes

Symptoms

• Sporadic warnings, often with no lasting malfunction
• Individual messages or modules dropping out under load or in damp weather

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: onsemi.com, nxp.com, ti.com.