CVT Primary Pulley Speed Sensor Circuit
2014-2021 Mazda Mazda6 2.5L I4
Description
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.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
P3021 on Other Vehicles
Common Questions
What does code P3021 mean on a 2014-2021 Mazda Mazda6?
P3021 stands for "CVT Primary Pulley Speed Sensor Circuit". The primary (input) pulley speed sensor in the CVT is reporting erratic or no signal. The TCM requires this signal for ratio control.
What are the symptoms of P3021 on a Mazda Mazda6?
Common symptoms of P3021 include: Check Engine Light, Transmission stuck in one ratio, Erratic shifting, Speedometer malfunction, Limp mode, Delayed engagement.
What causes P3021 on a 2014-2021 Mazda Mazda6?
Common causes of P3021 include: Faulty primary pulley speed sensor, Damaged tone ring, Sensor wiring damage, Contaminated sensor tip, TCM input circuit failure.