CVT Belt/Chain Slip Detected
2014-2021 BMW i3 Range Extender
Description
The TCM detected excessive slip in the CVT belt or chain. The input and output shaft speed ratio does not match the commanded pulley ratio.
Symptoms
- Check Engine Light
- Transmission shudder
- RPM flare without acceleration
- Whining noise from transmission
- Reduced acceleration
- Limp mode activation
Common Causes
- Worn CVT belt/chain
- Low CVT fluid level
- Degraded CVT fluid
- Worn pulleys
- CVT pressure solenoid failure
Diagnostic Steps
- Check CVT fluid level and condition
- Monitor input vs output shaft speed
- Check line pressure with scan tool
- Inspect CVT fluid for metal contamination
- Test pressure control solenoids
Repair Notes
CVT fluid replacement with OEM-specified fluid may resolve mild cases. Severe slip requires belt/chain and possibly pulley replacement.
Related Codes
Other Powertrain Codes
- P0070Ambient Air Temperature Sensor Circuit
- P0071Ambient Air Temperature Sensor Range/Performance
- P0072Ambient Air Temperature Sensor Circuit Low
- P0073Ambient Air Temperature Sensor Circuit High
- P0115Engine Coolant Temperature (ECT) Sensor 1 Circuit
- P0116ECT Sensor 1 Circuit Range/Performance
- P0117ECT Sensor 1 Circuit Low Input
- P0118ECT Sensor 1 Circuit High Input
- P0119ECT Sensor 1 Circuit Intermittent
- P0125Insufficient Coolant Temperature for Closed Loop Fuel Control
P3020 on Other Vehicles
Common Questions
What does code P3020 mean on a 2014-2021 BMW i3?
P3020 stands for "CVT Belt/Chain Slip Detected". The TCM detected excessive slip in the CVT belt or chain. The input and output shaft speed ratio does not match the commanded pulley ratio.
What are the symptoms of P3020 on a BMW i3?
Common symptoms of P3020 include: Check Engine Light, Transmission shudder, RPM flare without acceleration, Whining noise from transmission, Reduced acceleration, Limp mode activation.
What causes P3020 on a 2014-2021 BMW i3?
Common causes of P3020 include: Worn CVT belt/chain, Low CVT fluid level, Degraded CVT fluid, Worn pulleys, CVT pressure solenoid failure.