P3021high severityPowertrain
CVT Primary Pulley Speed Sensor Circuit
on 2015 Kia Forte 1.8L I4 · FWD
What this code means
The primary (input) pulley speed sensor in the CVT is reporting erratic or no signal. The TCM requires this signal for ratio control.
Symptoms
- Check Engine Light
- Transmission stuck in one ratio
- Erratic shifting
- Speedometer malfunction
- Limp mode
- Delayed engagement
Common causes
- Faulty primary pulley speed sensor
- Damaged tone ring
- Sensor wiring damage
- Contaminated sensor tip
- TCM input circuit failure
Diagnostic steps
- Read primary pulley speed PID
- Inspect sensor connector and wiring
- Check tone ring condition
- Test sensor resistance and air gap
- Compare primary to secondary sensor readings
Repair notes
Replace primary pulley speed sensor. Inspect tone ring for damage or contamination.
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