Not assigned in the generic OBD-II standard - if your scan tool shows this code, it is manufacturer-specific; verify the meaning in your make's service information
The C0621 code means the vehicle's onboard diagnostic system has detected: Not assigned in the generic OBD-II standard - if your scan tool shows this code, it is manufacturer-specific; verify the meaning in your make's service information. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- hard
- Estimated cost
- Unknown until the make-specific meaning is confirmed
Common Symptoms
- Depends entirely on the manufacturer-specific meaning - no generic definition exists
Probable Causes (Ranked by Likelihood)
- This code ID is not defined by the generic OBD-II standard; a stored instance is manufacturer-assigned High
Frequently Asked Questions
Why can't I find a standard definition for C0621?
Because the generic OBD-II standard does not assign this ID. Any stored C0621 is a manufacturer-specific code; its meaning must come from your make's service documentation.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Confirm the code with a make-specific (enhanced) scan tool.
-
Look the code up in your manufacturer's official service information - generic OBD-II references do not define it.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Commonly Affected Vehicles
- 2010-2020 Lincoln Navigator
- 2012-2022 Mercedes-Benz E-Class
- 2011-2021 BMW 5 Series
- 2013-2023 Cadillac Escalade
Related Codes
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