Test Description

WARNING: This page is about a different variant/trim than selected.

The number below refers to the step number on the diagnostic table.

4: This test must not be performed until the HO2S heater has cooled and stabilized for at least 15 minutes. Heater resistance is typically about 10 ohms at room temperature.

DTC P0135, P0141, P0155, or P0161

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module (ECM) Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check-Engine Controls?	-	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Clear the DTCs with a scan tool. Start the engine. Allow the engine to reach operating temperature. Refer to Scan Tool Data List . Observe the DTC info parameter with a scan tool for at least 30 seconds. Did the DTC fail this ignition?	-	Go to Step 4	Go to Step 3
3	Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 4	Go to Intermittent Conditions
4	Turn OFF the ignition. Allow the HO2S to cool for at least 15 minutes. Disconnect the affected heated oxygen sensor (HO2S). Measure the resistance from the heater low control circuit of the HO2S to the ignition 1 voltage circuit of the HO2S, at the sensor side. Is the resistance within the specified range?	2-20 ohm	Go to Step 5	Go to Step 10
5	Test for an intermittent and for a poor connection at the affected HO2S 1 harness connector. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Repairs. Did you find and correct the condition?	-	Go to Step 12	Go to Step 6
6	Disconnect the engine control module (ECM). Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Repairs. Did you find and correct the condition?	-	Go to Step 12	Go to Step 7
7	Measure the resistance of the affected HO2S 1 heater low control circuit between the ECM harness connector and the HO2S harness connector. Refer to Circuit Testing in Wiring Systems. Is the resistance more than the specified value?	5 ohm	Go to Step 9	Go to Step 8
8	Measure the resistance of the affected HO2S ignition 1 voltage circuit between the HO2S harness connector and the appropriate ignition 1 voltage circuit fuse. Refer to Circuit Testing in Wiring Systems. Is the resistance more than the specified value?	5 ohm	Go to Step 9	Go to Step 11
9	Repair the circuit that measures high resistance. Refer to Wiring Repairs and Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems. Did you complete the repair?	-	Go to Step 12	-
10	Replace the HO2S. Refer to Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1 , Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 2 , Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 1 , or Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 2 . Did you complete the replacement?	-	Go to Step 12	-
11	Replace the ECM. Refer to Engine Control Module (ECM) Replacement . Did you complete the replacement?	-	Go to Step 12	-
12	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 13
13	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List	System OK