FAQ
TL;DR: One documented case shows coding "00000" after an RB4 swap; "hazard lights come on and flash all the time." Root cause is immobilizer and coding, not wiring. [Elektroda, adamski123, post #16984787]
Why it matters: This FAQ helps Audi A4 B6 owners and techs quickly stop post-swap hazard flashing and restore normal cluster/AC behavior.
Quick Facts
- Symptom pattern: engine starts, then hazards flash continuously; cluster coding reads 00000. [Elektroda, adamski123, post #16984787]
- Root fix guidance: “make it immo and everything will return to normal,” then code the cluster. [Elektroda, jokerro, post #16985305]
- Key learning: at least one key must be adapted to the replacement clocks. [Elektroda, jokerro, post #16985305]
- Some report two keys stop the immobilizer LED from blinking during adaptation. [Elektroda, mar.wo, post #16985701]
- Cross-year swap (2001 car → 2003 RB4 8E0 920 900K) can trigger hazards and disable AC if immo is off. [Elektroda, bartlomiej242, post #17342864]
Why do my hazard lights flash after installing an RB4 cluster in an A4 B6?
The cluster was installed with immobilizer disabled and no proper adaptation. The car starts, but the cluster reports coding 00000 and triggers hazards. Restore immobilizer, adapt the cluster to ECU, and recode the instruments. This behavior was observed immediately after startup in the reported case. “The car starts, but after a moment the hazard lights come on and flash all the time.” [Elektroda, adamski123, post #16984787]
How do I stop the flashing without replacing wiring or modules?
Re-enable the immobilizer, adapt the replacement RB4 to the ECU, then code the cluster. Add keys to the new cluster before considering immo-off again. Experienced users report normal operation after proper immo adaptation and key learning. As one put it: “make it immo and everything will return to normal.” [Elektroda, jokerro, post #16985305]
What is “immo off” and why is it risky here?
“Immo off” disables the immobilizer in the ECU or cluster. In RB4 swaps, running immo off can cause hazards to flash and other modules to misbehave. Restoring immobilizer and adapting the cluster usually resolves these issues. This aligns with practitioner advice to enable immobilizer and code correctly after swaps. [Elektroda, jokerro, post #16985305]
How many keys must I adapt to the replacement RB4 cluster?
Adapt at least one key to the new cluster so the car authorizes properly. Some techs recommend adapting two keys to keep the immobilizer indicator from blinking during the process. If the LED blinks, complete adaptation with the required key count. [Elektroda, mar.wo, post #16985701]
What tool and channels are used for RB4 adaptation (A4 B6)?
Use VCDS to access 17-Instruments. Login with the new cluster’s PIN, then go to Adaptation, channel 50, to match ECU/cluster. After that, log in and use channel 21 for key learning. Follow the prompts carefully to avoid security lockouts during steps. [Elektroda, adamski123, post #16987776]
Can you give me a 3-step how-to for channel 50 adaptation and key learning?
- 17-Instruments → 11-Login with new cluster PIN; 10-Adaptation → channel 50 → enter old cluster/ECU PIN → Save.
- Cycle ignition OFF/ON; re-login with the adapted PIN.
- Adapt keys: channel 21 → set number of keys needed (do not enter 0) → Test/Save and present keys. [Elektroda, adamski123, post #16987776]
I typed 0 keys in channel 21 and got an error—why?
Entering 0 requests zero keys, which the system rejects. The controller responds with an error, and key programming will not proceed. Set the exact number of keys you intend to adapt and follow Test/Save correctly. Avoid repeated failed attempts to prevent timeouts. [Elektroda, adam7009, post #16988102]
After channel 50, I can’t log in with the old PIN—what now?
If login fails after adaptation, the pairing may not have completed or the cluster security block is inconsistent. Some technicians solve this by synchronizing ECU and cluster data directly in EEPROM. “Sometimes it happens that the adaptation does not work.” [Elektroda, kukiz1986, post #17112943]
My AC panel stopped working after the swap—related to immobilizer/coding?
Yes. Users report the AC panel not working when the cluster is swapped with immobilizer disabled or coding mismatched. Completing immobilizer adaptation and correct instrument coding restores normal HVAC communication over the cluster gateway. Re-enable immobilizer and finish coding first. [Elektroda, jokerro, post #16985305]
Does cross-year cluster swapping (e.g., 2001 car with 2003 RB4 8E0 920 900K) cause issues?
It can. One user swapped a 2003 RB4 (900K) into a 2001 A4 and saw hazard flashing and AC inoperative with immo off. Proper adaptation and coding are required when mixing years and part suffixes (E vs K). [Elektroda, bartlomiej242, post #17342864]
VCDS shows three keys in memory but won’t code mine—what does that mean?
The cluster can show existing keys from its donor vehicle. If it sees three keys yet won’t accept yours, the car and cluster aren’t matched. Perform channel 50 adaptation, then clear and relearn the correct number of keys for your vehicle. [Elektroda, bartlomiej242, post #17343511]
What does cluster coding 00000 indicate after the swap?
Coding 00000 means the instruments lack proper feature coding for the vehicle configuration. You must code the cluster to the car’s options after immobilizer adaptation. Leaving 00000 can coincide with the hazard flashing behavior after start. [Elektroda, adamski123, post #16984787]
Channel 50 won’t pull VIN from the ECU—what’s my next step?
If channel 50 doesn’t show system/VIN pull, the cluster’s security block or EEPROM may be inconsistent. Technicians fix this by moving the security block or pairing in EEPROM directly, then reattempting adaptation. This approach helped when standard steps failed. [Elektroda, adamski123, post #16989813]
Is there a regional expert who can perform this adaptation if diagnostics fail?
A contributor from Podkarpacie offered on-vehicle service after diagnostic attempts failed, noting mixed-up clocks can block both OBD and service mode procedures. Consider expert help when cars have multiple prior interventions. [Elektroda, jokerro, post #17343469]
What is VCDS in this context?
VCDS is diagnostic software used to access control modules like 17-Instruments and perform Login and Adaptation. In this thread, it’s used for channel 50 immobilizer matching and channel 21 key learning. Follow on-screen prompts to prevent lockouts. [Elektroda, adamski123, post #16987776]
Bottom line: will this always work via diagnostics?
No. One expert said adaptation “does not work” sometimes. In those cases, pairing the cluster to the ECU by editing EEPROM data resolves the mismatch. After that, keys can be learned and hazards stop. [Elektroda, kukiz1986, post #17112943]
