Ambient Temperature Sensor Circuit - HVAC
2018-2018 Lincoln MKX 2.7L V6 EcoBoost
The 2018 Lincoln MKX is equipped with a 2.7L V6 turbocharged gasoline engine. Below you'll find detailed b0621 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.
Description
Malfunction in the ambient (outside) temperature sensor used by the automatic climate control system.
Symptoms
- Incorrect outside temp display
- Auto climate control not adjusting for outside temp
- A/C compressor may not engage
- Defrost strategy incorrect
Common Causes
- Faulty ambient sensor
- Sensor mounted near heat source
- Wiring damage
- Sensor connector corroded
Diagnostic Steps
- Compare sensor reading to actual outside temperature
- Inspect sensor location for heat sources
- Test sensor resistance
- Check wiring
- Inspect connector
Repair Notes
Replace ambient temperature sensor. Ensure it is properly mounted away from heat sources.
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
B0621 on Other Vehicles
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Common Questions
What does code B0621 mean on a 2018-2018 Lincoln MKX?
B0621 stands for "Ambient Temperature Sensor Circuit - HVAC". Malfunction in the ambient (outside) temperature sensor used by the automatic climate control system.
What are the symptoms of B0621 on a Lincoln MKX?
Common symptoms of B0621 include: Incorrect outside temp display, Auto climate control not adjusting for outside temp, A/C compressor may not engage, Defrost strategy incorrect.
What causes B0621 on a 2018-2018 Lincoln MKX?
Common causes of B0621 include: Faulty ambient sensor, Sensor mounted near heat source, Wiring damage, Sensor connector corroded.
Last updated: March 2026