Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC B3843 02: Outside Air Quality Sensor Circuit Short to GroundDTC B3843 05: Outside Air Quality Sensor Circuit Short to Battery or Open
DTC B3843 08: Outside Air Quality Sensor Circuit Invalid Signal
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Air Quality Sensor Ignition | -- | B3843 05 | -- | -- |
Air Quality Sensor Signal | B3843 02 | B3843 05 | B3843 05 | B3843 08 |
Air Quality Sensor Ground | -- | B3843 05 | -- | -- |
Circuit/System Description
The HVAC control module detects exhaust gas by an air quality sensor. The air quality sensor is a 3-wire sensor with an ignition voltage circuit, a ground circuit and a signal circuit.
The information is pulse width modulation (PWM) signal generated on the output pin.
The HVAC control module evaluates the information of the air quality sensor and closes the recirculation flap while in the automatic mode, as soon as the concentration of pollutants exceeds a preset value.
Conditions for Running the DTC
| • | Ignition ON. |
| • | The HVAC control module is ON. |
Conditions for Setting the DTC
B3843 02
No PWM is detected and the signal is low.
B3843 05
No PWM is detected and the signal is high.
B3843 08
The Sensor sends a 5% PWM signal indicating an internal sensor short circuit or open circuit.
Action Taken When the DTC Sets
The automatic recirculation mode is disabled.
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Automatic HVAC Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify that DTC B3843 08 is not present.
| ⇒ | If DTC is present, replace the B108 Air Quality Sensor. |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the B108 Air Quality Sensor.
- Test for less than 5 Ω between the ground circuit terminal 2 and ground.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.
- Verify the scan tool Odor Sensor parameter is greater than 95%.
- Install a 3 A fused jumper wire between the following signal circuit terminal 3 and the ground circuit terminal 2. Verify the scan tool Odor Sensor parameter is less than 5%.
- If all circuits test normal, replace the B108 Air Quality Sensor.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or a open/high resistance. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K33 HVAC Control Module. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage or open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for HVAC Control Module replacement, setup, and programming |
