Wiper System Voltage Supply
The B0494 code means the vehicle's onboard diagnostic system has detected: Wiper System Voltage Supply. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $50 - $300 (parts and labor)
Basic scanners skip body codes entirely. BlueDriver reads airbag, HVAC, lighting, and BCM codes through your phone.
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Common Symptoms
- Auto-wipe feature not functioning
- Rain sensor not detecting precipitation
- Wipers activate without rain
- Auto-wipe sensitivity adjustment has no effect
Probable Causes (Ranked by Likelihood)
- Faulty rain sensor on windshield Very High
- Dirty or obstructed rain sensor lens High
- Rain sensor adhesive pad degraded Moderate
- BCM rain sensor input fault Low
Step-by-Step Diagnostic Procedure
-
Clean rain sensor lens area on windshield
-
Test rain sensor output with scan tool
-
Inspect rain sensor mounting and adhesive
-
Check wiring from sensor to BCM
Frequently Asked Questions
What is the rain sensor?
An optical sensor mounted on the windshield near the rearview mirror that detects water droplets and automatically activates the wipers.
Why does my auto-wipe not work after windshield replacement?
The rain sensor adhesive pad or alignment may not have been properly reinstalled during windshield replacement.
Can I clean the rain sensor?
The external windshield should be kept clean. The sensor itself is internal and should not be touched with cleaning products.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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