For 1990-2009 cars

### DTC Descriptor

DTC B0158 0E: OAT Sensor Circuit Below Threshold
DTC B0158 0D: OAT Sensor Circuit Above Threshold

### Circuit/System Description

The control modules on this vehicle monitor the battery voltage through the battery positive voltage circuits. This vehicle has multiple modules that will set this DTC.

### Conditions for Running the DTC

The ignition is turned ACC or RUN

### Conditions for Setting the DTC

#### B0158 0E

Once the voltage is out of range the code shall re-main current until the voltage becomes less than 0.28 ohm for 1 second.

#### B0158 0D

Once the voltage is out of range the code shall re-main current until the voltage becomes greater than 36.1 K ohm for 1 second.

### Conditions for Clearing the DTC

• | The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.

• | A current DTC clears when the malfunction is no longer present.

### Circuit/System Verification

The numbers below refer to the step numbers on the diagnostic table.

1. This step tests for the proper operation of the circuit in the high voltage range.

2. This step tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, observe the Appropriate parameter.

Does the scan tool indicate that the Appropriate parameter is within the specified range?

0.3 ohms - 3.6 K ohms

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the appropriate air temperature sensor.
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the Appropriate parameter.

Does the scan tool indicate that the Appropriate parameter is greater than the specified value?

0.3 ohms

Go to Step 4

Go to Step 5

4 |

1. Turn OFF the ignition.
2. Connect a 3-amp fused jumper wire between the signal circuit of the appropriate air temperature sensor and the low reference circuit of the appropriate air temperature sensor.
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the Appropriate parameter.

Does the scan tool indicate that the Appropriate Air Temp parameter is less than the specified value?

3.6 K ohms

Go to Step 9

Go to Step 6

5 | Test the signal circuit of the appropriate air temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10
6 | Test the signal circuit of the appropriate air temperature sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 7
7 | Test the low reference circuit of the appropriate air temperature sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 8
8 | Test the following signal circuits for a short to voltage:

• | Ambient air temperature sensor

• | Ambient light sensor

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

9 | Inspect for poor connections at the harness connector of the appropriate air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11
10 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12
11 | Replace the appropriate air temperature sensor. Did you complete the replacement? | -- | Go to Step 13 | --
12 | Replace the HVAC control module. Refer to HVAC Module Assembly Replacement . Did you complete the replacement? | -- | Go to Step 13 | --
13 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK