Adaptive Cruise Control Radar Sensor Malfunction
What does C0203 mean?
The C0203 code means the vehicle's onboard diagnostic system has detected: Adaptive Cruise Control Radar Sensor Malfunction. This is a moderate severity code.
Common Symptoms
- Adaptive cruise control not available
- Radar sensor blocked warning message
- Forward collision warning disabled
- ACC system fault on dashboard
- Distance display to vehicle ahead not showing
Probable Causes (Ranked by Likelihood)
- Radar sensor blocked by dirt, snow, or ice Very High
- Radar sensor out of alignment from bumper impact High
- Failed radar sensor unit Moderate
- Radar sensor wiring or connector fault Low
Step-by-Step Diagnostic Procedure
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Clean radar sensor area on front bumper or grille
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Inspect for bumper damage that could misalign sensor
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Scan ACC module for sensor DTCs
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Check radar sensor connector for damage
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Perform radar sensor alignment if recently impacted
Frequently Asked Questions
Where is the radar sensor located?
The adaptive cruise control radar sensor is typically mounted in the front bumper, behind the grille emblem, or behind a cover plate in the lower bumper area.
Can a bumper repair affect the radar sensor?
Yes. Even minor bumper work can misalign the radar sensor. After any front-end repair, the sensor should be recalibrated using a specialized alignment target and scan tool.
Why does the sensor warning come on in bad weather?
Heavy rain, snow, or ice buildup on the sensor face can block the radar signal. The system will display a warning and disable ACC until the sensor is clear.