Code result
C0420
Adaptive Cruise Control Module Internal Performance
Moderate severity
What it means
The adaptive cruise control module has reported an internal performance fault — for example self-test failure, supply voltage out of range or invalid configuration. ACC is disabled.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
ACC module internal fault
highOne of the most commonly reported causes for this code — check this first.
Supply voltage out of range
mediumA plausible cause — test and verify before replacing parts.
Module configuration invalid after part exchange
lowLess common, but worth ruling out after the more likely causes.
Related help
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