Engine-Codes - Lincoln - B121D Lincoln

B121D Lincoln Code - Rear HVAC Mode Control Input Circuit Short

- Code Popularity: 631 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
Table of contents
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What are the Possible Causes of the DTC B121D Lincoln?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Rear HVAC Mode Control
  • Rear HVAC Mode Control harness is open or shorted
  • Rear HVAC Mode Control circuit poor electrical connection
  • Faulty Heating, Ventilation, and Air-Conditioning (HVAC) Module

Code Tech Notes

B121D:11 Rear HVAC Mode Control Input Circuit Short to Ground
B121D:15 Rear HVAC Mode Control Input Circuit Short to Battery or Open

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How to Fix the DTC B121D Lincoln?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the B121D Lincoln code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

What Does the B121D Lincoln Code Mean?

Under normal operation, the rear auxiliary control is supplied a 5-volt reference and ground from the Heating, Ventilation, and Air-Conditioning (HVAC) Module. When the auxiliary blower motor speed, airflow mode or temperature control is adjusted, the HVAC module reads the voltage from the rear auxiliary climate controls on the auxiliary blower motor speed, airflow mode, and temperature control feedback circuits to determine the requested setting. The OBDII code sets when the HVAC module senses an open, or short to ground or voltage on the rear auxiliary climate controls temperature input circuit.

B121D Lincoln Code - Rear HVAC Mode Control Input Circuit Short

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