U0002

U0002 is a High Speed CAN Communication Bus Performance code, indicating the HS-CAN (typically 500 kbps powertrain/chassis bus) is communicating but with degraded signal integrity, retransmissions, or off-spec timing. This is the same family as U0029 but specifically flags the high-speed leg. Cheapest-first: verify the 60-ohm key-off resistance at DLC pins 6 and 14; HS-CAN absolutely must read 60 ohms or you have a terminator problem. Then scope the bus and look at the actual eye pattern: clean HS-CAN swings are CAN-H from 2.5V (idle/recessive) up to 3.5V (dominant) and CAN-L from 2.5V down to 1.5V, with the differential reading 0V recessive and 2V dominant. Slow rise/fall times, overshoot, or asymmetric voltages indicate a wiring problem or a module with a failing transceiver. Check shield/drain grounds if the harness has them. Caveat: poorly installed aftermarket dashcams, OBD-II GPS trackers, and insurance dongles are notorious for loading down HS-CAN and triggering U0002. Always unplug aftermarket OBD devices before condemning factory modules.

Vehicle-specific patterns: 2011-2016 Ford F-150 EcoBoost generates U0002 from a known PCM HS-CAN driver weakness; TSB 14-0194 addresses some cases. 2007-2014 GM trucks with HS-GMLAN see U0002 from C200 connector corrosion at the firewall on diesel trucks. 2008-2014 Dodge/Ram TIPM sets U0002 when the TIPM CAN gateway IC begins failing. 2007-2013 BMW E70 X5 sees U0002-equivalent (A0BC) from PT-CAN wiring damage near the valley pan on N62/N63 engines from heat exposure. Estimated repair: $100 to $1600.