Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSMERCURY2009MARINER HYBRID, AWDREPAIR AND DIAGNOSISQUICK LOOKUPSDTC INDEX - (HYBRID)CLIMATE CONTROL SYSTEM DTCSHVAC MODULE DTC CHART
2009 Mercury Mariner Hybrid, AWD
HVAC Module DTC Chart
2009 Mercury Mariner Hybrid, AWDSECTION HVAC Module DTC Chart
HVAC MODULE DIAGNOSTIC TROUBLE CODE (DTC) LIST
| DTC | Description | Action to Take |
|---|---|---|
| B1251 | Air Temperature Internal Sensor Circuit Open | GO to PINPOINT TEST A . |
| B1253 | Air Temperature Internal Sensor Circuit Short to Ground | GO to PINPOINT TEST A . |
| B2783 | Interior Humidity Sensor to DATC Short Circuit | GO to PINPOINT TEST B . |
| B2784 | Interior Humidity Sensor to DATC Open Circuit | GO to PINPOINT TEST B . |
| B1255 | Air Temperature External Sensor Circuit Open | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B1257 | Air Temperature External Sensor Circuit Short to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B129B | Driver Blend Door Actuator, Drive Circuit(s) Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B129C | Driver Blend Door Actuator, Feedback Circuit Open or Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B129D | Driver Blend Door Actuator, Feedback Circuit Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B129F | Passenger Blend Door Actuator, Drive Circuit(s) Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12A0 | Passenger Blend Door Actuator, Feedback Circuit Open or Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12A1 | Passenger Blend Door Actuator, Feedback Circuit Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12A2 | Passenger Blend Door Actuator, Slow or Door Obstructed | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12A4 | Mode Door Actuator, Drive Circuit(s) Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12A5 | Mode Door Actuator, Feedback Circuit Open or Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12A6 | Mode Door Actuator, Feedback Circuit Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12A7 | Mode Door Actuator, Slow or Door Obstructed | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12A9 | Recirc Door Actuator, Drive Circuit(s) Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12AF | Front Blower Motor Relay Drive Circuit Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12B0 | Front Blower Motor Relay Drive Circuit Open or Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12B1 | Front Blower Motor PWM Drive Circuit Shorted to Battery Voltage | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12B2 | Front Blower Motor PWM Drive Circuit Open or Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12B8 | Driver Blend Door Actuator, Slow or Door Obstructed | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B12B9 | Vref (5V) Drive Circuit Shorted to Battery Voltage | REPAIR circuit LH111 (BNAVH) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. |
| B12BA | Vref (5V) Drive Circuit Shorted to Ground | REPAIR circuit LH111 (BNAVH) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. |
| B1342 | Module Is Faulted | INSTALL a new HVAC module. REFER to CLIMATE CONTROL . |
| B1676 | Battery Voltage Out of Range | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B2426 | Passenger Solar Radiation Sensor Circuit Open | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B2427 | Passenger Solar Radiation Sensor Circuit Short to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B2477 | Module Configuration Failure | INSTALL a new HVAC module. REFER to CLIMATE CONTROL . |
| B2795 | Driver Solar Radiation Sensor Circuit Short to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B2796 | Driver Solar Radiation Sensor Circuit Open | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B2826 | Front Evaporator Temp Sensor Circuit Failure | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B2827 | Front Evaporator Temp Sensor Short to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B297B | Blend Door Actuator, Drive Circuit(s) Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B297C | Driver Blend Door Actuator, Drive Circuit(s) Open | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B297D | Driver Blend Door Actuator, Drive Circuit(s) Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B297E | Passenger Blend Door Actuator, Drive Circuit(s) Open | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B297F | Passenger Blend Door Actuator, Drive Circuit(s) Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B298A | Mode Door Actuator, Drive Circuit(s) Open | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B298B | Mode Door Actuator, Drive Circuit(s) Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B298C | Recirc Door Actuator, Drive Circuit(s) Open | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| B298D | Recirc Door Actuator, Drive Circuit(s) Shorted to Ground | REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS . |
| U0140 | Lost Communication With Generic Electronic Module (GEM) | CLEAR The DTCs. REPEAT the self-test. If the DTC returns, REFER to MODULE COMMUNICATIONS NETWORK to diagnose the lost communication with the GEM. |
| U0300 | Internal Control Module Software Incompatibility | INSTALL a new HVAC module. REFER to CLIMATE CONTROL . |
| U2050 | No Application Present | INSTALL a new HVAC module. REFER to CLIMATE CONTROL . |
| U2051 | One or More Calibration Files Missing/Corrupt | INSTALL a new HVAC module. REFER to CLIMATE CONTROL . |
| All Other DTCs | - | REFER to the Master DTC Chart in MULTIFUNCTION ELECTRONIC MODULES . |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.