U3036Communication Authentication Signal Performance
- Generic OBD-II code · Network
- Turns on the check-engine light
- How the car detects it
- U3036 judges authentication over time rather than a single bad frame: checks keep failing, cannot be completed, or sender and receiver lose step, for example in their freshness counters. AUTOSAR SecOC shows why this differs from U3035: a receiver retries when no freshness value is available or the crypto service is busy and only gives up after a configured number of build or verify attempts. Ford stores U3036 in the 2023 Super Duty PCM; SSM 51497 explains that it is logged while the PCM keeps monitoring as the CAN bus goes to sleep, and needs no action without other codes, MIL or drivability faults. TSB 23-2421 covers 6.8L and 7.3L trucks with MIL, P061B and U0140, cured by new PCM software. After a TRON module swap Ford also lists U3036 among codes from keys that were not redistributed.
- What you may notice
- Code stored after a self-test or key-off without complaints
- MIL together with P061B or U0140 on some engines
- Secured functions working only intermittently
- Likely causes
- LikelyMonitoring software flags authentication during bus sleep or wake-up
- PossibleFreshness counters of sender and receiver out of step
- PossibleKeys not redistributed after module replacement
- RareSending module intermittently missing on the bus
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €0 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.