OBD-II code · Network (extended)
U3036 Communication Authentication Signal Performance
Authentication signal arrives within tolerances but timing or content drifted from expected behavior.
Is it safe to drive with U3036?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyAuthentication timing drift
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–5 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Can Bus, Security Module
Related codes
- U3033Control Module Security Certificate Missing/Invalid
- U3034Communication Authentication Key/Certificate Missing/Invalid
- U3035Communication Authentication Signal Invalid Data
- U3500Control Module Input Power A Circuit Range/Performance
- U3501Control Module Input Power A Circuit Low
- U3502Control Module Input Power A Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.