• | 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. |
Circuit | Short to Ground | Open | Short to Voltage | Signal Performance |
---|---|---|---|---|
HO2S 2 Heater Voltage Supply | Opens fuse | P0036, P0037, P0141 | -- | P0141 |
HO2S 2 Heater Low Control | P0036, P0037, | P0036, P0037, P0141 | P0036, P0038, P0141 | P0141 |
HO2S 2 Signal High | P0137 | -- | P0138 | -- |
HO2S 2 Reference Ground | -- | -- | -- | -- |
Heated oxygen sensors (HO2S) are used for fuel control and post-catalyst monitoring. The HO2S 2 compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S 2 must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S 2 minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by an ignition voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S 2 heater low control circuit, through a low side driver within the Engine Control Module (ECM). The ECM uses pulse-width modulation (PWM) to control the HO2S 2 heater operation to maintain a specific HO2S 2 operating temperature range.
The ECM monitors the voltage on the HO2S 2 heater low control circuit for heater fault diagnosis. If the ECM detects that the HO2S 2 heater low control circuit voltage is not within a specified range, DTC P0036 sets.
The ECM monitors the voltage on the HO2S 2 heater low control circuit for heater fault diagnosis. If the ECM detects that the HO2S 2 heater low control circuit voltage is below a specified range, DTC P0037 sets.
The ECM monitors the voltage on the HO2S 2 heater low control circuit for heater fault diagnosis. If the ECM detects that the HO2S 2 heater low control circuit voltage is above a specified range, DTC P0038 sets.
If the ECM detects that the heater current is not within the expected range, DTC P0141 sets.
• | The Ignition 1 Signal parameter is between 10-18 volts. |
• | The engine speed is more than 80 RPM. |
• | DTC P0036, P0037, and P0038 run continuously when the above conditions are met for 1 second. |
• | DTCs P0036, P0037, P0038, P0121, P0122, P0123, P0137, P0138, P0140, P0221, P0222, P0223, P0335, P0336, P0338, P2232, P2271, P2271 are not set. |
• | The Ignition 1 Signal parameter is between 10-18 volts. |
• | The modeled exhaust gas temperature is between 360-500°C (680-932°F). |
• | The engine off soak time is greater than 120 seconds. |
• | The engine is not in decel fuel cut-off. |
• | The intake air temperature (IAT) is greater than -30°C (-22°F). |
• | DTC P0141 runs continuously. |
• | The ECM detects that the difference between the expected and the actual HO2S 2 heater low control circuit voltage is more than a calibrated value. |
• | DTCs P0036, P0037, and P0038 set when the above condition is met for 4 seconds continuously, or for 50 seconds cumulatively. |
• | The ECM detects that the HO2S 2 heater current is more than 2.5 amps or less than 0.25 amp. |
• | DTC P0141 sets within 30 seconds during the heater current test when the above condition is met. |
DTC P0036, P0037, P0038, P0141 are Type B DTCs.
DTC P0036, P0037, P0038, P0141 are Type B DTCs.
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
⇒ | If the test lamp does not illuminate, test the HO2S 2 heater voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all components connected to the fuse and replace as necessary. |
⇒ | If the test lamp illuminates, test the HO2S 2 heater low control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If the test lamp is not ON steady or flashing, test the HO2S 2 heater low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Notice: Refer to Heated Oxygen Sensor Resistance Learn Reset Notice in the Preface section.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |