B1021
TPMS Sensor Frequency Mismatch
2012-2015 BMW 320i 2.0L I4 Turbo N20
Low SeverityBodyGeneric (SAE)
Description
One or more TPMS sensors are transmitting on a different frequency than the vehicle receiver expects.
Symptoms
- TPMS warning light on
- Some sensors not reading
- New sensor not recognized
Common Causes
- Aftermarket sensor with wrong frequency
- European/Asian frequency sensor on US vehicle
- Mixed sensor brands
- Incorrect replacement sensor part number
Diagnostic Steps
- Verify sensor frequency with TPMS tool
- Check sensor part number compatibility
- Compare sensor frequency to vehicle specification
- Test each sensor individually
Repair Notes
Replace mismatched sensors with correct frequency sensors. US vehicles typically use 315 MHz, European/Asian use 433 MHz.
Related Codes
Other Body Codes
- B0001Driver Frontal Stage 1 Deployment Control
- B0002Driver Frontal Stage 2 Deployment Control
- B0003Passenger Frontal Stage 1 Deployment Control
- B0004Passenger Frontal Stage 2 Deployment Control
- B0005Driver Knee Airbag Deployment Circuit
- B0006Passenger Knee Airbag Deployment Circuit
- B0007Rear Left Side Airbag Deployment Circuit
- B0008Rear Right Side Airbag Deployment Circuit
- B0009Rear Center Airbag Deployment Circuit
- B0010Driver Side Airbag Deployment
B1021 on Other Vehicles
Common Questions
What does code B1021 mean on a 2012-2015 BMW 320i?
B1021 stands for "TPMS Sensor Frequency Mismatch". One or more TPMS sensors are transmitting on a different frequency than the vehicle receiver expects.
What are the symptoms of B1021 on a BMW 320i?
Common symptoms of B1021 include: TPMS warning light on, Some sensors not reading, New sensor not recognized.
What causes B1021 on a 2012-2015 BMW 320i?
Common causes of B1021 include: Aftermarket sensor with wrong frequency, European/Asian frequency sensor on US vehicle, Mixed sensor brands, Incorrect replacement sensor part number.