The heated oxygen sensor (HO2S) produces a voltage that varies between 100-900 mV under normal operating conditions. The engine control module (ECM) produces a bias voltage on the HO2S signal circuit of 420-480 mV. The engine control module (ECM) supplies the sensor the reference ground circuit. The ECM monitors the signal voltage to determine if the exhaust is lean or rich. The oxygen sensor voltage is high when the exhaust is rich, and low when the exhaust is lean. The ECM constantly monitors the HO2S signal during the Closed Loop operation. If the ECM detects that the decel fuel cut-off rich-to-lean transition time is too long, DTC P0139 or P013A will be set for bank 1 sensor 2, or DTC P0159 or P013C will be set for bank 2 sensor 2. If the ECM detects that the decel fuel cut-off rich-to-lean transition is not timely, DTC P013E will be set for bank 1 sensor 2, or DTC P014A will be set for bank 2 sensor 2.
This diagnostic procedure supports the following DTC:
• | DTC P0139 or P013A HO2S Slow Response Bank 1 Sensor 2 |
• | DTC P0159 or P013C HO2S Slow Response Bank 2 Sensor 2 |
• | DTC P013E HO2S Delayed Response Bank 1 Sensor 2 |
• | DTC P014A HO2S Delayed Response Bank 2 Sensor 2 |
• | DTC P0021, P0024, P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0135, P0137, P0138, P0139, P0140, P0141, P0151, P0152, P0155, P0157, P0158, P0159, P0160, P0161, P0201-P0208, P0221, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P0279, P0280, P0282, P0283, P0300, P0301-P0308, P0335, P0336, P0340, P0341, P0345, P0346, P0351-P0358, P0365, P0366, P0390, P0391, P0442, P0443, P0446, P0449, P0453, P0454, P0455, P0458, P0459 and P0496 are not set. |
• | The decel fuel cut-off system is activate. |
• | The rear HO2S voltage is more than 0.59 V during the Decel Fuel Cut-Off. |
• | During the Decel Fuel Cut-Off (DFCO), the accumulated air mass is more than 15 grams during a transition from high voltage to low voltage. |
• | Ignition 1 voltage is greater than 10.5 volts. |
• | The rear HO2S is ready or under any given function, the rear HO2S Decel Fuel Cut-Off (DFCO) Test fails. |
• | The rear HO2S is near mildew condition. |
• | The rear HO2S heater is stable. |
• | The front HO2S is ready. |
• | The value of the front HO2S measured is more than 10. |
• | DTC P0139 or P0159 runs continuously once the above conditions are met for more than 4 seconds. |
• | The decel fuel cut-off system is activate. |
• | The front and the rear HO2S are ready. |
• | The power voltage is greater than 10.4 V. |
• | The rear HO2S internal resistance is not more than the specified resistance. |
• | The exhaust temperature of rear HO2S is more than or equal to 400°C (752°F). |
• | The rear HO2S voltage is the value when the exhaust is rich. |
• | DTC P013A or P013C runs continuously once the above conditions are met for more than 4 seconds. |
• | The decel fuel cut-off system is activated. |
• | The rear HO2S voltage is between 0.14-0.59 volts after decel fuel cut-off. |
• | The front and the rear HO2S are ready. |
• | The front HO2S voltage is less than 0.14 volts. |
• | The power voltage is greater than 10.4 V. |
• | The rear HO2S internal resistance is not more than the specified resistance. |
• | The exhaust temperature of the rear HO2S is more than or equal to 400°C (752°F). |
• | The rear HO2S voltage is the value when the exhaust is rich or the accumulated oxygen storage capacity is more than 15 grams. |
• | DTC P013E or P014A runs continuously once the above conditions are met for more than 4 seconds. |
The ECM detects that the rear HO2S voltage signal is 140 mV for 2 seconds During Decel Fuel Cut-Off.
The ECM detects that the rear HO2S Slow Response time is more than 0.8 second and voltage is between 0.2-0.4 volts.
The ECM detects that the rear HO2S Delayed Response time is greater than 6 seconds.
• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs but fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
• | The control module turns OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail (MIL). |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warmup cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Turn the MIL OFF with a scan tool and clear the DTC. |
Step | Action | Values | Yes | No | ||||||||||||||||||||
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Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||||||||||||
2 |
Does the voltage react instantly when performing the above action? | -- | Go to Step 3 | Go to Step 4 | ||||||||||||||||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||||||||||||||||
4 |
Is the voltage less than the specified value? | 25 mV | Go to Step 5 | Go to Step 7 | ||||||||||||||||||||
5 |
Is the voltage less than the specified value? | 25 mV | Go to Step 6 | Go to Step 8 | ||||||||||||||||||||
6 |
Is the resistance of any circuit more than the specified value? | 5 Ω | Go to Step 12 | Go to Step 9 | ||||||||||||||||||||
7 | Test the HO2S high signal circuit for an open or high resistance. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 | ||||||||||||||||||||
8 | Test the HO2S low signal circuit for an open or high resistance. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 | ||||||||||||||||||||
9 | The HO2S is detecting a rich or lean exhaust condition or may be contaminated. Check for one of the following conditions:
Repair any of the above or similar engine conditions as necessary. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 10 | ||||||||||||||||||||
10 | Test for intermittent and poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | ||||||||||||||||||||
11 | Test for an intermittent and poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 | ||||||||||||||||||||
12 | Repair the circuits with high resistance. Refer to Wiring Repairs and Heated Oxygen Sensor Wiring Repairs . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||||||||||||||||
13 | Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 . | -- | Go to Step 15 | -- | ||||||||||||||||||||
14 | Replace the ECM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||||||||||||||||
15 |
Does the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 16 | ||||||||||||||||||||
16 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |