TPMS Sensor Frequency Mismatch
2009-2012 Ford Flex 3.5L V6
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
- B0010Driver Side Airbag Deployment
- B0011Driver Side Airbag Deployment Circuit Open
B1021 on Other Vehicles
Ford Bronco
2021-2024 2.3L I4 EcoBoost
Ford Bronco
2021-2024 2.7L V6 EcoBoost
Ford Bronco Raptor
2022-2024 3.0L V6 EcoBoost
Ford Bronco Sport
2021-2024 1.5L I3 EcoBoost
Ford Bronco Sport
2021-2024 2.0L I4 EcoBoost
Ford Crown Victoria
1998-2011 4.6L V8 Modular 2V
Ford E-150
1997-2014 4.6L V8 Triton
Ford E-150
1997-2014 5.4L V8 Triton
Common Questions
What does code B1021 mean on a 2009-2012 Ford Flex?
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 Ford Flex?
Common symptoms of B1021 include: TPMS warning light on, Some sensors not reading, New sensor not recognized.
What causes B1021 on a 2009-2012 Ford Flex?
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.