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B1948 OBD-II Trouble Code: Climate Control Water Temperature Sensor Circuit Short To Ground

diagnostic check engine light

B1948 code definition

The B1948 code is a manufacturer-specific body code related to the climate control system. In this case, the engine control module (ECM) has detected a fault or a short to ground in the circuit for the climate control water temperature sensor.

What the B1948 code means

A code B1948 will be stored when the ECM detects a coolant temperature signal circuit fault between the instrument pack and the air conditioning/climate control module (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 68-degrees Fahrenheit. If a circuit fault occurs between the instrument pack and the A/CCM, the A/CCM will substitute a default value of 169-degrees Fahrenheit.

What causes the B1948 code?

Several problems may cause a B1948 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 B1948 code?

Symptoms of a B1948 code may include: * Check engine or warning light may illuminate * The air condition/climate control system may not function correctly (for example, blowing warm air only)

How does a mechanic diagnose the B1948 code?

A mechanic may use several methods to diagnose a B1948 trouble code, including: * Utilize an OBD-II scanner to check for a stored B1948 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 B1948 code?

Because a vehicle’s safe driving operation will not be impacted due to faults that store a B1948 code, this code is not considered a serious code. When this code appears, it is recommended to take your vehicle to your local service center or mechanic for repair and diagnosis as soon as possible.

What repairs can fix the B1948 code?

Several repairs can fix a B1948 trouble code and include:

Need help with a B1948 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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