Active Suspension Control Module Communication Error
What does C0257 mean?
The C0257 code means the vehicle's onboard diagnostic system has detected: Active Suspension Control Module Communication Error. This is a moderate severity code.
Common Symptoms
- Service ride control message
- All four corners revert to default damping
- Suspension warning light on
- Ride quality noticeably different
- Other modules may show communication DTCs
Probable Causes (Ranked by Likelihood)
- CAN bus wiring fault to suspension module Very High
- Suspension control module power supply issue High
- Corroded module connector Moderate
- Suspension control module internal failure Moderate
- CAN bus termination resistor failure Low
Step-by-Step Diagnostic Procedure
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Scan all modules for communication-related DTCs
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Check CAN bus wiring at the suspension control module connector
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Verify power and ground at the suspension module
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Inspect the module connector for corrosion, bent pins, or water intrusion
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Check for CAN bus resistance -- should measure approximately 60 ohms between CAN high and low
Frequently Asked Questions
What happens when the suspension module loses communication?
The active shocks revert to a default damping rate -- usually a medium setting. You lose the adaptive ride quality but the vehicle is still safe to drive. The ride may feel stiffer or softer than normal.
Can a CAN bus problem affect other systems?
Yes. The CAN bus is a shared communication network. A fault in one area can affect multiple modules. Look for communication codes in other modules like ABS, engine, and transmission.
How do I test the CAN bus?
Using a multimeter, measure resistance between CAN high and CAN low at the OBD-II port. Normal reading is approximately 60 ohms. You can also use an oscilloscope to check for clean CAN bus waveforms.