C0238 code meaning
Speed Wheel-to-Wheel Mismatch
What C0238 means
C0238 does not appear in the publicly available J2012 code lists. GM uses it: the terminal-check bulletin PIP5094 for 2014 and older GM cars and light trucks names it as a chassis keyword, and AA1Car's table of GM ABS codes calls it Wheel Speed Mismatch, which fits the title. GM does not publish its setting rule for this number. A related GM test on the 2011 Saab 9-5 shows the principle: above 14 km/h, brake off and driving straight, a wheel reading more than 20 percent off the others is treated as a fault. Typical reasons are one tire of a different size or pressure, a spare wheel, a damaged tone ring or a sensor with too much air gap. ABS and traction control are normally switched off until the next ignition cycle.
C0238 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.2 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of C0238
- ABS and traction control warning lamps on
- ABS and traction control disabled for the rest of the trip
Common causes of C0238
- Most likelyOne tire with different size, wear or pressure, or a space-saver spare fitted
- PossibleCracked, corroded or wrong tone ring on one wheel
- PossibleWheel speed sensor loose or with excessive air gap, or worn wheel bearing
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Wheel speed sensorTone ringTiresABS control module
What each part of C0238 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 38 | The exact fault in that area. |
What to do next
- Note C0238 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C0238
What does C0238 mean?
C0238 means "Speed Wheel-to-Wheel Mismatch". C0238 does not appear in the publicly available J2012 code lists. It is a generic code, so it means the same on every make.
Is it safe to drive with C0238?
Drive gently and only to a workshop. With C0238 the car can go into limp mode (reduced power) to protect itself.
Will C0238 fail an emissions test?
C0238 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C0238 to fix?
Difficulty: medium. A typical repair takes 0.2 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will C0238 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.