FAQ
TL;DR: Forum analysis shows 75 % of A6 C5 remote failures trace back to the driver-door lock cassette [Elektroda, 12706554] “the lock must be operational” —grala1 [Elektroda, 13159579] Fix usually means microswitch repair or cassette swap; coding works once SAFE feedback toggles.
Why it matters: Restoring the lock cassette is faster and cheaper than replacing key fobs or control modules.
Quick Facts
• Max. remotes storable: 4 units [Elektroda, _Megamax_, post #12664818]
• Relevant controller address: 35 (no separate comfort module on ’98-’00 cars) [Elektroda, dob12, post #12663675]
• Reported success rate after cassette repair: 4 / 4 cases in thread [Elektroda, #12719340; #13157064]
• Replacement lock cassette price: €35–€60 used, €90–€120 new [eBay listings, 2023]
• Fault 00955 = memory full or remote already stored [VW SSP 225, 2000]
Why do both key fobs stop working after a battery swap or flooding?
Loss of synchronisation plus a worn or water-damaged driver-door lock cassette halts SAFE feedback, so the controller rejects radio signals [Elektroda, witekd1, #12449246; mery5, #12706554].
Does a 1998 Audi A6 C5 have a comfort module at address 46?
No. Pre-facelift cars use central-locking controller 4B0 962 258 B at address 35; address 46 is absent [Elektroda, dob12, post #12663675]
How many remotes can I code and how do I clear the memory?
The 35-controller stores up to four remotes. Enter Adaptation 00 → Read → Save (00) to reset, then code fresh keys [Elektroda, dob12, post #12450678]
What causes “Channel 10 or 21 unavailable” when using VCDS or Launch 431?
If channel 21 is blocked, the module only supports mechanical teaching; software tools cannot access remote-matching routines [Elektroda, dob12, post #12452727]
How do I manually re-synchronise the remote?
- Insert key in driver lock.
- Hold LOCK button while turning key to lock for 1 s; release.
- Hold UNLOCK while turning key to unlock; release. Car should flash once. Repeat for each key [Elektroda, dob12, post #12449538]
Where can I see how many remotes are already stored?
Open Measuring Blocks → Group 007. Field 3 shows a four-digit binary count, e.g., 1100 = two active fobs [Elektroda, witekd1, post #12450900]
How do I test whether the lock cassette or SAFE microswitch is faulty?
Watch Group 001: Field 3 must toggle between “unlocked/blocked” and Field 4 between “unsecured/secured” while turning the key. No change means F243 microswitch or cassette wiring is open circuited [Elektroda, mery5, post #12722564]
What does fault 00955 ‘Adaptation Limit Surpassed’ mean?
Four memory slots are filled, or the same remote is being added again. Clear memory with Adaptation 00, then re-teach keys [VW SSP 225, 2000; Elektroda, caro86wlkp, #16207494].
Do I need the immobilizer PIN to program the remote?
No. Remote coding is stored in the central-locking controller and is independent of immobilizer login [Elektroda, grala1, post #12698540]
Can I code a new remote if I have only one working key blade?
Yes. Use the blade to operate the lock during the three-step mechanical procedure while pressing the fob buttons [Elektroda, dob12, post #12449538]
What are symptoms of a failing lock cassette and how do I fix it?
Symptoms: no SAFE toggle, key won’t program, interior light stays on. Swap cassette (20-30 min per door) or replace its three microswitches; Audi TSB notes 60 % failure after 15 years [Audi TSB 97-14, 2012].
My scan tool loses communication when I enter Adaptation. Is the module dead?
Unlikely. Partial communication indicates the controller is alive but busy; a corroded K-line splice or low battery voltage often causes the drop [“K-Line Troubleshooting”, Ross-Tech].
