OBD-II Diagnostic Trouble Code
C0237 — Vehicle Speed Sensor (drive train)
C0237 indicates a fault with the drivetrain vehicle speed signal used by the brake module. The module saw the drivetrain speed signal missing or not matching wheel speed sensor data. Meaning varies by OEM; on some trucks it refers to the transmission output speed sensor signal shared over the data network.
Severity 3/5
Truck-relevant
Service this week
Severity
Service this week
Vehicle Speed Sensor (drive train)
Code
C0237
Category
Chassis
Subsystem
Speed
Truck-relevant
Yes
What this means for truckers
C0237 (Vehicle Speed Sensor Drive Train) — drivetrain-side VSS.
Before you replace parts — try this first
C0237 on the Speed system is most often failed transmission output speed sensor — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
ABS and traction lights on, speedometer may drop out or read wrong, and cruise control may not engage. Transmission shift quality may change if the same sensor is affected. Braking feel is normal.
Common causes
- CommonFailed transmission output speed sensor ($120–$400)
- CommonWiring or connector fault at the transmission ($80–$300)
- OccasionalNetwork communication fault between transmission and brake modules ($100–$500)
- RareWrong tire size or axle ratio programmed ($80–$200)
How to fix
Check for transmission and network codes and compare speed signals on a scan tool
When to use: First step
Inspect output speed sensor connector and wiring
When to use: Speed signal drops out
Replace the output speed sensor
When to use: Sensor output is weak or missing
Verify tire size and axle ratio programming
When to use: After tire or axle changes
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → C0235 — Vehicle Speed Sensor Circuit
- → C0249 — Brake Boost Sensor Out of Range
- → C0265 — EBCM Relay Circuit
- → C0277 — Brake Pedal Position Switch Circuit
- → C0282 — Brake Pedal Travel Sensor Circuit
Frequently Asked Questions
Can I drive with code C0237?
C0237 is severity 3 — plan service within a few days. Performance is likely degraded already (you may feel reduced power, harsher shifts, or slightly worse fuel economy). Continuing to drive risks additional damage to adjacent components.
How much does it cost to fix C0237 on a commercial truck?
Total repair cost ranges $80–$500 depending on the root cause. The cheapest fix is usually the first one listed below — Failed transmission output speed sensor — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will C0237 fail a DOT inspection?
C0237 is generally not a direct DOT inspection fail item by itself. Inspectors focus on safety-critical systems (brakes, steering, tires, lights, hours-of-service). However, the check engine light alone can trigger additional inspection scrutiny. Best practice: fix the code and clear it before a planned inspection.
What's the difference between C0237 and related codes?
C0237 is closely related to: C0235 (Vehicle Speed Sensor Circuit), C0249 (Brake Boost Sensor Out of Range), C0265 (EBCM Relay Circuit), C0277 (Brake Pedal Position Switch Circuit). These codes share the same subsystem (speed) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only C0237 is set without the companions, the issue is more isolated.
How do I prevent C0237 from coming back after a repair?
For C0237 (Vehicle Speed Sensor (drive train)), prevention centers on the speed system. Inspect wheel speed sensor wiring at PM (rodents love it). Keep ABS tone rings clean.