
OBD-II · CODE FAMILY
Codes U00xx — what they mean
U00xx is a family of 116 manufacturer-specific OBD2 codes covering network and electrical faults. Each U00xx code below links to its own page with causes, diagnosis and the parts to fix it.
116 codesNetwork systems

01All codes in this family
One rich, indexed page — not thousands of empty ones. Each code links to its own page.
| Code | Meaning — click to open the code page | System | Severity |
|---|---|---|---|
| U0001 | This code is concerned with the communications circuit betwe → /auto/codes/u0001/ This code is concerned with the communications circuit between control modules throughout the vehicle. This communications circuit is most often refer | Network | Medium |
| U0002 | High Speed CAN Communication Bus Performance → /auto/codes/u0002/ High Speed CAN Communication Bus Performance | Network | Medium |
| U0003 | High Speed CAN Communication Bus (+) Open → /auto/codes/u0003/ High Speed CAN Communication Bus (+) Open | Network | Medium |
| U0004 | High Speed CAN Communication Bus (+) Low → /auto/codes/u0004/ High Speed CAN Communication Bus (+) Low | Network | Medium |
| U0005 | High Speed CAN Communication Bus (+) High → /auto/codes/u0005/ High Speed CAN Communication Bus (+) High | Network | Medium |
| U0006 | High Speed CAN Communication Bus (-) Open → /auto/codes/u0006/ High Speed CAN Communication Bus (-) Open | Network | Medium |
| U0007 | High Speed CAN Communication Bus (-) Low → /auto/codes/u0007/ High Speed CAN Communication Bus (-) Low | Network | Medium |
| U0008 | High Speed CAN Communication Bus (-) High → /auto/codes/u0008/ High Speed CAN Communication Bus (-) High | Network | Medium |
| U0009 | High Speed CAN Communication Bus (-) shorted to Bus (+) → /auto/codes/u0009/ High Speed CAN Communication Bus (-) shorted to Bus (+) | Network | Medium |
| U0010 | Medium Speed CAN Communication Bus → /auto/codes/u0010/ Medium Speed CAN Communication Bus | Network | Medium |
| U0011 | Medium Speed CAN Communication Bus Performance → /auto/codes/u0011/ Medium Speed CAN Communication Bus Performance | Network | Medium |
| U0012 | Medium Speed CAN Communication Bus (+) Open → /auto/codes/u0012/ Medium Speed CAN Communication Bus (+) Open | Network | Medium |
| U0013 | Medium Speed CAN Communication Bus (+) Low → /auto/codes/u0013/ Medium Speed CAN Communication Bus (+) Low | Network | Medium |
| U0014 | Medium Speed CAN Communication Bus (+) High → /auto/codes/u0014/ Medium Speed CAN Communication Bus (+) High | Network | Medium |
| U0015 | Medium Speed CAN Communication Bus (-) Open → /auto/codes/u0015/ Medium Speed CAN Communication Bus (-) Open | Network | Medium |
| U0016 | Medium Speed CAN Communication Bus (-) Low → /auto/codes/u0016/ Medium Speed CAN Communication Bus (-) Low | Network | Medium |
| U0017 | Medium Speed CAN Communication Bus (-) High → /auto/codes/u0017/ Medium Speed CAN Communication Bus (-) High | Network | Medium |
| U0018 | Medium Speed CAN Communication Bus (-) shorted to Bus (+) → /auto/codes/u0018/ Medium Speed CAN Communication Bus (-) shorted to Bus (+) | Network | Medium |
| U0019 | Low Speed CAN Communication Bus → /auto/codes/u0019/ Low Speed CAN Communication Bus | Network | Medium |
| U0020 | Low Speed CAN Communication Bus Performance → /auto/codes/u0020/ Low Speed CAN Communication Bus Performance | Network | Medium |
| U0021 | Low Speed CAN Communication Bus (+) Open → /auto/codes/u0021/ Low Speed CAN Communication Bus (+) Open | Network | Medium |
| U0022 | Low Speed CAN Communication Bus (+) Low → /auto/codes/u0022/ Low Speed CAN Communication Bus (+) Low | Network | Medium |
| U0023 | Low Speed CAN Communication Bus (+) High → /auto/codes/u0023/ Low Speed CAN Communication Bus (+) High | Network | Medium |
| U0024 | Low Speed CAN Communication Bus (-) Open → /auto/codes/u0024/ Low Speed CAN Communication Bus (-) Open | Network | Medium |
| U0025 | Low Speed CAN Communication Bus (-) Low → /auto/codes/u0025/ Low Speed CAN Communication Bus (-) Low | Network | Medium |
| U0026 | Low Speed CAN Communication Bus (-) High → /auto/codes/u0026/ Low Speed CAN Communication Bus (-) High | Network | Medium |
| U0027 | Low Speed CAN Communication Bus (-) shorted to Bus (+) → /auto/codes/u0027/ Low Speed CAN Communication Bus (-) shorted to Bus (+) | Network | Medium |
| U0028 | When a diagnostic trouble code U0404 is presented, it genera → /auto/codes/u0028/ When a diagnostic trouble code U0404 is presented, it generally indicates that the powertrain control module (PCM), transmission control module (TCM), | Network | Medium |
| U0029 | Vehicle Communication Bus A Performance → /auto/codes/u0029/ Vehicle Communication Bus A Performance | Network | Medium |
| U0030 | Vehicle Communication Bus A (+) Open → /auto/codes/u0030/ Vehicle Communication Bus A (+) Open | Network | Medium |
| U0031 | Vehicle Communication Bus A (+) Low → /auto/codes/u0031/ Vehicle Communication Bus A (+) Low | Network | Medium |
| U0032 | Vehicle Communication Bus A (+) High → /auto/codes/u0032/ Vehicle Communication Bus A (+) High | Network | Medium |
| U0033 | Vehicle Communication Bus A (-) Open → /auto/codes/u0033/ Vehicle Communication Bus A (-) Open | Network | Medium |
| U0034 | Vehicle Communication Bus A (-) Low → /auto/codes/u0034/ Vehicle Communication Bus A (-) Low | Network | Medium |
| U0035 | Vehicle Communication Bus A (-) High → /auto/codes/u0035/ Vehicle Communication Bus A (-) High | Network | Medium |
| U0036 | Vehicle Communication Bus A (-) shorted to Bus A (+) → /auto/codes/u0036/ Vehicle Communication Bus A (-) shorted to Bus A (+) | Network | Medium |
| U0037 | Vehicle Communication Bus B → /auto/codes/u0037/ Vehicle Communication Bus B | Network | Medium |
| U0038 | Vehicle Communication Bus B Performance → /auto/codes/u0038/ Vehicle Communication Bus B Performance | Network | Medium |
| U0039 | Vehicle Communication Bus B (+) Open → /auto/codes/u0039/ Vehicle Communication Bus B (+) Open | Network | Medium |
| U0040 | Vehicle Communication Bus B (+) Low → /auto/codes/u0040/ Vehicle Communication Bus B (+) Low | Network | Medium |
| U0041 | Vehicle Communication Bus B (+) High → /auto/codes/u0041/ Vehicle Communication Bus B (+) High | Network | Medium |
| U0042 | Vehicle Communication Bus B (-) Open → /auto/codes/u0042/ Vehicle Communication Bus B (-) Open | Network | Medium |
| U0043 | Vehicle Communication Bus B (-) Low → /auto/codes/u0043/ Vehicle Communication Bus B (-) Low | Network | Medium |
| U0044 | Vehicle Communication Bus B (-) High → /auto/codes/u0044/ Vehicle Communication Bus B (-) High | Network | Medium |
| U0045 | Vehicle Communication Bus B (-) shorted to Bus B (+) → /auto/codes/u0045/ Vehicle Communication Bus B (-) shorted to Bus B (+) | Network | Medium |
| U0046 | Vehicle Communication Bus C → /auto/codes/u0046/ Vehicle Communication Bus C | Network | Medium |
| U0047 | Vehicle Communication Bus C Performance → /auto/codes/u0047/ Vehicle Communication Bus C Performance | Network | Medium |
| U0048 | Vehicle Communication Bus C (+) Open → /auto/codes/u0048/ Vehicle Communication Bus C (+) Open | Network | Medium |
| U0049 | Vehicle Communication Bus C (+) Low → /auto/codes/u0049/ Vehicle Communication Bus C (+) Low | Network | Medium |
| U0050 | Vehicle Communication Bus C (+) High → /auto/codes/u0050/ Vehicle Communication Bus C (+) High | Network | Medium |
| U0051 | Vehicle Communication Bus C (-) Open → /auto/codes/u0051/ Vehicle Communication Bus C (-) Open | Network | Medium |
| U0052 | Vehicle Communication Bus C (-) Low → /auto/codes/u0052/ Vehicle Communication Bus C (-) Low | Network | Medium |
| U0053 | Vehicle Communication Bus C (-) High → /auto/codes/u0053/ Vehicle Communication Bus C (-) High | Network | Medium |
| U0054 | Vehicle Communication Bus C (-) shorted to Bus C (+) → /auto/codes/u0054/ Vehicle Communication Bus C (-) shorted to Bus C (+) | Network | Medium |
| U0055 | Vehicle Communication Bus D → /auto/codes/u0055/ Vehicle Communication Bus D | Network | Medium |
| U0056 | Vehicle Communication Bus D Performance → /auto/codes/u0056/ Vehicle Communication Bus D Performance | Network | Medium |
| U0057 | Vehicle Communication Bus D (+) Open → /auto/codes/u0057/ Vehicle Communication Bus D (+) Open | Network | Medium |
| U0058 | Vehicle Communication Bus D (+) Low → /auto/codes/u0058/ Vehicle Communication Bus D (+) Low | Network | Medium |
| U0059 | Vehicle Communication Bus D (+) High → /auto/codes/u0059/ Vehicle Communication Bus D (+) High | Network | Medium |
| U0060 | Vehicle Communication Bus D (-) Open → /auto/codes/u0060/ Vehicle Communication Bus D (-) Open | Network | Medium |
| U0061 | Vehicle Communication Bus D (-) Low → /auto/codes/u0061/ Vehicle Communication Bus D (-) Low | Network | Medium |
| U0062 | Vehicle Communication Bus D (-) High → /auto/codes/u0062/ Vehicle Communication Bus D (-) High | Network | Medium |
| U0063 | Vehicle Communication Bus D (-) shorted to Bus D (+) → /auto/codes/u0063/ Vehicle Communication Bus D (-) shorted to Bus D (+) | Network | Medium |
| U0064 | Vehicle Communication Bus E → /auto/codes/u0064/ Vehicle Communication Bus E | Network | Medium |
| U0065 | Vehicle Communication Bus E Performance → /auto/codes/u0065/ Vehicle Communication Bus E Performance | Network | Medium |
| U0066 | Vehicle Communication Bus E (+) Open → /auto/codes/u0066/ Vehicle Communication Bus E (+) Open | Network | Medium |
| U0067 | Vehicle Communication Bus E (+) Low → /auto/codes/u0067/ Vehicle Communication Bus E (+) Low | Network | Medium |
| U0068 | Vehicle Communication Bus E (+) High → /auto/codes/u0068/ Vehicle Communication Bus E (+) High | Network | Medium |
| U0069 | Vehicle Communication Bus E (-) Open → /auto/codes/u0069/ Vehicle Communication Bus E (-) Open | Network | Medium |
| U0070 | Vehicle Communication Bus E (-) Low → /auto/codes/u0070/ Vehicle Communication Bus E (-) Low | Network | Medium |
| U0071 | Vehicle Communication Bus E (-) High → /auto/codes/u0071/ Vehicle Communication Bus E (-) High | Network | Medium |
| U0072 | Vehicle Communication Bus E (-) shorted to Bus E (+) → /auto/codes/u0072/ Vehicle Communication Bus E (-) shorted to Bus E (+) | Network | Medium |
| U0073 | Please comment below describing your issue as well as the sp → /auto/codes/u0073/ Please comment below describing your issue as well as the specifics of your vehicle (make, model, year, miles, and engine).
To get a detailed, expedi | Network | Medium |
| U0074 | Control Module Communication Bus B Off → /auto/codes/u0074/ Control Module Communication Bus B Off | Network | Medium |
| U0075 | Control Module Communication Bus C Off → /auto/codes/u0075/ Control Module Communication Bus C Off | Network | Medium |
| U0076 | Control Module Communication Bus D Off → /auto/codes/u0076/ Control Module Communication Bus D Off | Network | Medium |
| U0077 | Control Module Communication Bus E Off → /auto/codes/u0077/ Control Module Communication Bus E Off | Network | Medium |
| U0078 | Control Module Communication Bus F Off → /auto/codes/u0078/ Control Module Communication Bus F Off | Network | Medium |
| U0079 | Control Module Communication Bus G Off → /auto/codes/u0079/ Control Module Communication Bus G Off | Network | Medium |
| U007A | Control Module Communication Bus H Off → /auto/codes/u007a/ Control Module Communication Bus H Off | Network | Medium |
| U007B | Control Module Communication Bus I Off → /auto/codes/u007b/ Control Module Communication Bus I Off | Network | Medium |
| U007C | Control Module Communication Bus J Off → /auto/codes/u007c/ Control Module Communication Bus J Off | Network | Medium |
| U007D | Control Module Communication Bus K Off → /auto/codes/u007d/ Control Module Communication Bus K Off | Network | Medium |
| U007E | Control Module Communication Bus L Off → /auto/codes/u007e/ Control Module Communication Bus L Off | Network | Medium |
| U007F | Control Module Communication Bus M Off → /auto/codes/u007f/ Control Module Communication Bus M Off | Network | Medium |
| U0080 | Vehicle Communication Bus F → /auto/codes/u0080/ Vehicle Communication Bus F | Network | Medium |
| U0081 | Vehicle Communication Bus F Performance → /auto/codes/u0081/ Vehicle Communication Bus F Performance | Network | Medium |
| U0082 | Vehicle Communication Bus F + Open → /auto/codes/u0082/ Vehicle Communication Bus F + Open | Network | Medium |
| U0083 | Vehicle Communication Bus F + Low → /auto/codes/u0083/ Vehicle Communication Bus F + Low | Network | Medium |
| U0084 | Vehicle Communication Bus F + High → /auto/codes/u0084/ Vehicle Communication Bus F + High | Network | Medium |
| U0085 | Vehicle Communication Bus F - Open → /auto/codes/u0085/ Vehicle Communication Bus F - Open | Network | Medium |
| U0086 | Vehicle Communication Bus F - Low → /auto/codes/u0086/ Vehicle Communication Bus F - Low | Network | Medium |
| U0087 | Vehicle Communication Bus F - High → /auto/codes/u0087/ Vehicle Communication Bus F - High | Network | Medium |
| U0088 | Vehicle Communication Bus F - Shorted to Bus F + → /auto/codes/u0088/ Vehicle Communication Bus F - Shorted to Bus F + | Network | Medium |
| U0089 | Vehicle Communication Bus G → /auto/codes/u0089/ Vehicle Communication Bus G | Network | Medium |
| U008A | Vehicle Communication Bus G Performance → /auto/codes/u008a/ Vehicle Communication Bus G Performance | Network | Medium |
| U008B | Vehicle Communication Bus G (+) Open → /auto/codes/u008b/ Vehicle Communication Bus G (+) Open | Network | Medium |
| U008C | Vehicle Communication Bus G (+) Low → /auto/codes/u008c/ Vehicle Communication Bus G (+) Low | Network | Medium |
| U008D | Vehicle Communication Bus G (+) High → /auto/codes/u008d/ Vehicle Communication Bus G (+) High | Network | Medium |
| U008E | Vehicle Communication Bus G (-) Open → /auto/codes/u008e/ Vehicle Communication Bus G (-) Open | Network | Medium |
| U008F | Vehicle Communication Bus G (-) Low → /auto/codes/u008f/ Vehicle Communication Bus G (-) Low | Network | Medium |
| U0090 | Vehicle Communication Bus G (-) High → /auto/codes/u0090/ Vehicle Communication Bus G (-) High | Network | Medium |
| U0091 | Vehicle Communication Bus G (-) shorted to Bus G (+) → /auto/codes/u0091/ Vehicle Communication Bus G (-) shorted to Bus G (+) | Network | Medium |
| U0092 | Vehicle Communication Bus H → /auto/codes/u0092/ Vehicle Communication Bus H | Network | Medium |
| U0093 | Vehicle Communication Bus H Performance → /auto/codes/u0093/ Vehicle Communication Bus H Performance | Network | Medium |
| U0094 | Vehicle Communication Bus H (+) Open → /auto/codes/u0094/ Vehicle Communication Bus H (+) Open | Network | Medium |
| U0095 | Vehicle Communication Bus H (+) Low → /auto/codes/u0095/ Vehicle Communication Bus H (+) Low | Network | Medium |
| U0096 | Vehicle Communication Bus H (+) High → /auto/codes/u0096/ Vehicle Communication Bus H (+) High | Network | Medium |
| U0097 | Vehicle Communication Bus H (-) Open → /auto/codes/u0097/ Vehicle Communication Bus H (-) Open | Network | Medium |
| U0098 | Vehicle Communication Bus H (-) Low → /auto/codes/u0098/ Vehicle Communication Bus H (-) Low | Network | Medium |
| U0099 | Vehicle Communication Bus H (-) High → /auto/codes/u0099/ Vehicle Communication Bus H (-) High | Network | Medium |
| U009A | Vehicle Communication Bus H (-) shorted to Bus H (+) → /auto/codes/u009a/ Vehicle Communication Bus H (-) shorted to Bus H (+) | Network | Medium |
| U009B | Vehicle Communication Bus I → /auto/codes/u009b/ Vehicle Communication Bus I | Network | Medium |
| U009C | Vehicle Communication Bus I Performance → /auto/codes/u009c/ Vehicle Communication Bus I Performance | Network | Medium |
| U009D | Vehicle Communication Bus J → /auto/codes/u009d/ Vehicle Communication Bus J | Network | Medium |
| U009E | Vehicle Communication Bus J Performance → /auto/codes/u009e/ Vehicle Communication Bus J Performance | Network | Medium |
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