C0071 explained: The vehicle speed signal from the PCM does not agree with the ABS wheel speed average. A transmission output speed sensor or CAN bus issue is the usual cause.
🎯 Top Causes & Probability
45%
#1 - Most Likely
Failed Transmission Output Speed Sensor
Sensor in the tail housing or extension housing fails. Replacement restores accurate speed data.
🔨 Part
$30-$120
👨🔧 Labor
$120-$280
⚡ DIY
Medium
30%
#2 - Check First
CAN Bus or Module Communication Fault
Intermittent loss of PCM speed broadcast. Look for U-codes in the ABS, PCM, and BCM.
🔨 Part
$0-$120
👨🔧 Labor
$120-$220
⚡ DIY
Medium
18%
#3 - Less Common
Tire Size Mismatch
Significantly different tire sizes across axles confuse the cross-check. Match tires and clear the code.
🔨 Part
$200-$800
👨🔧 Labor
$80-$160
⚡ DIY
Easy
🚗 Most Affected Vehicles
🔧 Step-by-Step Diagnosis
- Scan all modules and note any U-codes alongside C0071.
- Compare wheel speed average to PCM vehicle speed while rolling.
- Test the transmission output speed sensor with a meter or scan tool.
- If a U-code points at CAN, inspect the bus wiring at common pinch points.
- Replace the speed sensor or repair the bus as findings indicate.
❓ Frequently Asked Questions
Does an upsized tire trigger C0071?
Yes if the tire is significantly larger or only changed on two wheels. Match tires and reprogram speedometer if needed.
Will this affect the speedometer?
A failed transmission output sensor can make the speedometer drop to zero. ABS C0071 often pairs with that complaint.
Is the speed sensor expensive?
Most are $30-$80 plus an hour of labor.
Can a bad ABS module cause C0071?
Less common but possible. Rule out the sensor and CAN issues first.