OBD-II Code · Network
U0002
High Speed CAN Communication Bus Performance
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$100–$1,500
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
High-speed CAN bus performance fault.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Intermittent warnings
Likely causes
- Marginal wiringMost common
- Failing module
Read the full diagnostic procedureU0002 is a High Speed CAN Communication Bus Performance code, indicating the HS-CAN (typically 500 kbps powertrain/chassis bus) is communicating but…
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 patterns2011-2016 Ford F-150 EcoBoost generates U0002 from a known PCM HS-CAN driver weakness; TSB 14-0194 addresses some cases.
- 2011-2016Ford F-150 EcoBoost generates U0002 from a known PCM HS-CAN driver weakness; TSB 14-0194 addresses some cases.
- 2007-2014GM trucks with HS-GMLAN see U0002 from C200 connector corrosion at the firewall on diesel trucks.
- 2008-2014Dodge/Ram TIPM sets U0002 when the TIPM CAN gateway IC begins failing.
- 2007-2013BMW 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.
Look up another code
U0002 — frequently asked
What does a U0002 code mean?
High-speed CAN bus performance fault.
What causes a U0002 code?
Common causes: Marginal wiring; Failing module.
What are the symptoms of a U0002 code?
Typical symptoms: Intermittent warnings.
Is it safe to drive with a U0002 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $100-$1,500.
How do I diagnose a U0002 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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