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Old 07-07-2026, 05:53 AM   #3
elgyqc
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Join Date: Sep 2018
Location: Laval QC
Posts: 908
Garage
Quote:
Originally Posted by JFP in PA View Post
Error code 21: Airbag Ignition Circuit Driver fault

This means the car's computer has detected an open circuit, short, or communication failure with the driver's side airbag, indicating it may not deploy in a crash.

Most Likely Causes & Fixes

1. Faulty Clock Spring (most common)
2. Corroded or Loose Wiring
3. Low Voltage or Dying Battery
Thanks for the details JFP. My battery is good and the wiring appears good also.
I just happen to have a spare clock spring so I did a continuity test on it and am puzzled by the results... I get continuity from either pin on the harness connector to either pin of the airbag connector. The clock spring that was in the car gives the same results. Does this mean both are defective? I bought the spare one used a couple of years ago when I had a horn problem. I found a broken ground wire which I fixed. I can't remember if I put the fixed original back on the car our if I used the "new" one.
Update - after watching this video
https://www.youtube.com/watch?v=-UgL22uM8Tk
I learned that the connector shorts out the pins on the harness connector, so the above behavior is normal.
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Arctic Silver 2000 Boxster S - bought with a broken engine, back on the road with the engine replaced
Green 2000 Boxster 5-speed and 1978 928 auto
1987 924S 5-speed (Sold) - Blue 2000 Boxster 5 spd (Sold)

Last edited by elgyqc; 07-07-2026 at 06:15 AM. Reason: addition
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