C1238: Rear Right Wheel Speed Sensor Signal Noise (Toyota)
Severity: medium
What it means: C1238 is a Toyota ABS code for the right-rear wheel speed sensor. Toyota's manual describes it as a foreign object on the sensor tip, but it really means the sensor's signal is noisy, which can also come from a damaged sensor ring, wiring or a corroded connector.
Safe to drive? The regular brakes still work, but ABS and stability control may be off, so stopping on slippery roads can be harder. Get it checked.
Common symptoms
- ABS light on
- Traction or stability light on
- Brief unwanted ABS activation on some cars
Likely causes, ranked
- Corroded connector or damaged wiringDIY
- Debris or damage at the sensor or sensor ringShop
- Failed sensor (sealed in the hub bearing on some models)Shop
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Vehicle-specific notes
- 2007–2011 Toyota Yaris: On YarisWorld, an owner with C0210 and C1238 had brief unwanted ABS activation; members said to clean and grease the connector first, then replace the harness, then the bearing. Read the full answer · Source
DIY or shop?
DIY for cleaning and greasing the connector. Sensor or hub bearing replacement is often a shop job.
Before you replace parts
- Read all ABS codes; C0210 often sets with it.
- Inspect the right-rear sensor connector for corrosion and clean it.
- Check the wiring along the suspension for damage.
- Check your VIN for service bulletins before replacing the bearing.
Safety / mechanic note
Verify with a mechanic. ABS may be off, so stopping distances on slippery roads can be longer. A code points to a circuit or system, not always a specific part.
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