What Does B1947 Mean?
This code indicates the climate control module has detected a short to ground in the post-evaporator temperature sensor circuit. This sensor monitors air temperature after it passes through the evaporator core to help regulate A/C system performance. The module detected abnormally low voltage on the signal wire, indicating the circuit is making unintended contact with ground/chassis.
Common Causes
45%
Damaged or chafed wiring harness where sensor wiring contacts ground, typically near evaporator housing or HVAC unit mounting points
30%
Failed post-evaporator temperature sensor with internal short to ground
15%
Corroded or moisture-contaminated sensor connector causing short circuit path
10%
Climate control module internal fault creating false short-to-ground detection
Diagnostic Steps
1
Step 1: Visually inspect the post-evaporator sensor connector and wiring for obvious damage, corrosion, moisture intrusion, or chafing points. Check wire routing near sharp edges and mounting brackets.
2
Step 2: Disconnect the post-evaporator sensor connector at the sensor. Using a digital multimeter, measure resistance from the sensor signal wire (at the sensor side) to known good chassis ground. Reading should be >10k ohms (typically open circuit). Low resistance (<10 ohms) confirms short to ground in sensor.
3
Step 3: If sensor tests good, measure resistance from the harness side signal wire to ground with sensor disconnected. Low resistance indicates wiring harness short. Inspect harness carefully, especially inside dash and near evaporator housing, using wire schematics to trace routing.
4
Step 4: If no short found in wiring, reconnect sensor and backprobe signal wire at climate control module connector (sensor still connected). Measure voltage with key on - should read approximately 5V reference. If reading 0V with good wiring and sensor disconnected, suspect module fault.
5
Step 5: After repair (sensor replacement, wire repair, or connector cleaning), clear codes and operate A/C system through multiple cycles while monitoring live data for proper sensor temperature readings (typically 35-45°F when A/C active).
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
This code indicates the climate control module has detected a short to ground in the post-evaporator temperature sensor circuit. This sensor monitors air temperature after it passes through the evaporator core to help regulate A/C system performance. The module detected abnormally low voltage on the...
The most common cause of B1947 (Climate Control A/C Post Evaporator Sensor Circuit Short To Ground) is: Damaged or chafed wiring harness where sensor wiring contacts ground, typically near evaporator housing or HVAC unit mounting points
Typical repair costs for B1947 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving. This fault only affects automatic climate control precision and A/C efficiency, potentially causing inadequate cooling or excessive cycling. No immediate safety risk, but should be repaired for comfort and to prevent evaporator icing.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1947 to identify the root cause.
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Quick Info
Category
Body
System
Climate Control System
Difficulty
Type
Manufacturer
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