ABS Warning Lamp Circuit
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 b0421 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.
Description
Malfunction in the ABS warning lamp circuit. The lamp may not illuminate or may stay on incorrectly.
Symptoms
- ABS light does not come on during bulb check
- ABS light always on
- Cannot determine ABS system status
- Light flickering
Common Causes
- Burnt out lamp
- Cluster fault
- ABS module lamp driver failure
- Wiring issue
Diagnostic Steps
- Check lamp during key-on bulb check
- Scan ABS module for codes
- Test lamp drive circuit
- Inspect wiring from ABS module to cluster
Repair Notes
Replace ABS warning lamp or repair wiring circuit.
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
B0421 on Other Vehicles
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2003-2003 4.6L V8 DOHC
Lincoln Aviator
2004-2004 4.6L V8 DOHC
Lincoln Aviator
2005-2005 4.6L V8 DOHC
Lincoln Aviator
2020-2020 3.0L Twin-Turbo V6
Lincoln Aviator
2020-2020 3.0L V6 Twin Turbo
Lincoln Aviator
2020-2020 3.0L V6 Twin Turbo Hybrid
Lincoln Aviator
2021-2021 3.0L Twin-Turbo V6
Lincoln Aviator
2021-2021 3.0L V6 Twin Turbo
Common Questions
What does code B0421 mean on a 2018-2018 Lincoln MKX?
B0421 stands for "ABS Warning Lamp Circuit". Malfunction in the ABS warning lamp circuit. The lamp may not illuminate or may stay on incorrectly.
What are the symptoms of B0421 on a Lincoln MKX?
Common symptoms of B0421 include: ABS light does not come on during bulb check, ABS light always on, Cannot determine ABS system status, Light flickering.
What causes B0421 on a 2018-2018 Lincoln MKX?
Common causes of B0421 include: Burnt out lamp, Cluster fault, ABS module lamp driver failure, Wiring issue.
Last updated: March 2026