C0238 - Chassis Fault Code C0238 - Bromshydraulik & Trycksensorer
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System
Chassis (Brakes, Steering, Suspension)
Related Fault Codes
Technical Description
The EBCM continuously compares the frequency inputs from all four wheel speed sensors. DTC C0238 sets when a calibrated frequency mismatch threshold (typically > 5-10% deviation over a calibrated timeframe) between wheels or axle averages is exceeded during straight-ahead driving. Root causes include mismatched tire rolling circumferences, damaged or contaminated magnetic reluctor rings (improper pole count on replacement bearings), mechanical bearing runout affecting air gap, or intermittent signal attenuation.
Possible Causes
1. Avvikande däckdimensioner, kraftigt ojämnt däckslitage eller felaktigt lufttryck mellan hjulaxlar.
2. Felmonterat eftermarknadshjullager med felaktigt antal magnetiska poler på pulsgivarringen (t.ex. 44 poler istället för 48 poler).
3. Mekanisk skada, sprickor eller korrosionsuppbyggnad (rostsprängning) bakom tonring / magnetisk pulskodare.
4. Glapp eller axialt spel i hjullager som ändrar sensorns luftspalt dynamiskt under körning.
5. Internt signalbehandlingsfel i ABS/EBCM-styrenheten.
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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