🔢
P0855 is a low-severity diagnostic code. Reading freeze-frame data and any paired codes is the fastest way to narrow it down. See top-rated scanners on Amazon ↗
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🎯 Top Causes & Probability
50%
#1 - Most Likely
ABS / Traction Control Module Fault
The TCS controller is internally faulted or is not transmitting on the network. Usually paired with ABS or wheel speed codes.
🔨 Part
$200-$700
👨🔧 Labor
$120-$240
⚡ DIY Difficulty
Medium
30%
#2 - Check First
Wheel Speed Sensor Failure
A bad WSS prevents the TCS module from forming a valid traction signal, so the PCM sees nothing.
🔨 Part
$30-$150
👨🔧 Labor
$80-$180
⚡ DIY Difficulty
Medium
18%
#3 - Less Common
CAN Bus Wiring or Connector Issue
A break or corrosion in the CAN wiring between TCS and PCM prevents the message from reaching the engine controller.
🔨 Part
$10-$60
👨🔧 Labor
$100-$220
⚡ DIY Difficulty
Medium
🚗 Most Affected Vehicles
🚫 Is It Safe to Drive?
Yes - traction control is disabled but engine and brakes operate normally.
🔧 Step-by-Step Diagnosis
- Scan ALL modules - not just PCM - You will almost always find paired ABS, TCS, or wheel speed codes that point at the real failure.
- Check wheel speed sensors - Visually inspect each sensor and tone ring for damage. Compare WSS PIDs at the same speed.
- Inspect the TCS module connector - Especially on trucks - corrosion at the ABS module connector is a frequent cause.
- Test CAN communication - Use the scan tool to verify the TCS module is responding. If it is not online, suspect the module or its power/ground.
- Repair or replace the failed component - Module replacement may require programming. WSS replacement is straightforward.
❓ Frequently Asked Questions
Will my brakes still work?
Yes - regular braking is unaffected. Only the TCS/ABS computer assist is disabled.
Is TCS off dangerous?
Only in slippery conditions. Drive carefully in rain and snow until fixed.
Why is the ABS light also on?
TCS and ABS share the same module, so both lights often illuminate together.
Will it pass inspection?
State-by-state. Some states ignore ABS/TCS lights, others fail any active light.
Can I just clear the code?
It will return as soon as the underlying fault is detected. Diagnose, do not just clear.