2017 Mazda MX-5 Rf OBD2 Code B1949 Climate Control Water Temperature Sensor Circuit Failure

B1949 code definition

The B1949 code is a manufacturer-specific body code related to the climate control system . In this case, the engine control module (ECM) has detected a failure in the circuit for the climate control water temperature sensor.

What the B1949 code means

A code B1949 will be stored when the ECM detects a coolant temperature signal circuit fault between the instrument pack and air conditioning/climate control unit (A/CCM) . The A/CCM receives an engine coolant temperature voltage signal from the instrument pack.

The A/CCM monitors the engine coolant temperature circuit for open circuit, high resistance and short circuit conditions. If a fault is present, a DTC will be flagged. If a circuit fault occurs between the coolant temperature sensor and the instrument pack, the instrument pack output will default to a voltage equal to 20 °C (68 °F). If a circuit fault occurs between the instrument pack and the A/CCM, the A/CCM will substitute a default value of 76 °C (169 °F).

What causes the B1949 code?

Several problems may cause a B1949 code including:

• Damaged or defective wiring and related electrical components
• Signal circuit between instrument pack and A/CCM short circuit to ground
• Harness/wiring problems between heater valve and climate control module
• Fault or failure at one (or more) of the air mixing/blending flaps
• Fault in the pressurized A/C system , including condenser fan , compressor, refrigerant pressures/leaks
• Damaged or defective heater fan
• Damaged or defective climate control module

What are the symptoms of the B1949 code?

Symptoms of a B1949 code may include:

• Check engine or warning light may illuminate
• The air condition/climate control system may not function correctly (for example, only blowing warm air when air conditioner is cranked on)

How does a mechanic diagnose the B1949 code?

A mechanic may use several methods to diagnose a B1949 trouble code, including:

• Utilize an OBD-II scanner to check for a stored B1949 trouble code
• Visually inspect wiring and related electrical components for damage or defects
• Visually inspect for any leaks in the A/CCM system
• Check operation of pressured air conditioning system
• Check the fuse for the heater valve to see if blown or damaged
• Check the connection to the heater valve for damage or loose connectors or corrosion on the valve itself
• Check the evaporator discharge temperature sensor(s) for damage or defect
• Test the voltage, current, and resistance on the heater valve

How serious is the B1949 code?

Because a 2017 Mazda MX-5 rf's safe driving operation will not be impacted due to faults that store a B1949 code, this code is not considered a serious code. When this code appears, it is recommended to take your 2017 Mazda MX-5 rf to your local service center or mechanic for repair and diagnosis as soon as possible.

What repairs can fix the B1949 code?

Several repairs can fix a B1949 trouble code and include:

• Repair or replace any damaged, corroded, open, or shorted wiring and related electrical components
• Repair any possible leaks in the A/CCM system
• Replace damaged, defective, or blown fuses
• Replace damaged or defective heater valve
• Replace damaged or defective evaporator discharge sensor
• Clear all codes, test-drive your 2017 Mazda MX-5 rf, and rescan to see if any codes reappear

Additional information related to a B1949 code

With any repairs related to the electrical components of your 2017 Mazda MX-5 rf, it is recommended to review your 2017 Mazda MX-5 rf's service manual, and if possible utilize the assistance of a professional to avoid additional costly repairs.

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B1949