In order to maintain low emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), the engine controls system uses a 3-way catalytic converter. The catalyst within the converter promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust gas. This reaction converts these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces the NOx which converts into nitrogen. The powertrain control module (PCM) monitors this process using Bank 1 of the HO2S 2, which is located in the exhaust stream past the 3-way catalytic converter. Bank 1 of the HO2S 2 produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalyst's ability to effectively convert the exhaust emissions. If the catalyst is functioning correctly, the Bank 1 of the HO2S 2 signal will be far less active than the signal that is produced by Bank 1 of the HO2S 1. This indicates that the 3-way catalytic converter's oxygen storage capacity is below an acceptable threshold.
The PCM performs this diagnostic test at idle. When the conditions for running this DTC are met, the following occurs:
• | DTCs P0101-P0103, P0106-P0108, P0112, P0113, P0117, P0118, P0125, P0131-P0135, P0137, P0138, P0140, P0141, P0151-P0155, P0157, P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0200, P0300, P0325, P0327, P0335, 336, P0341-P0343, P0351-P0358, P0443, P0446, P0449, P0502, P0503, P0506, P0507, P1120, P1125, P1133, P1134, P1153, P1154, P1220, P1221, P1275, P1276, P1280, P1281, P1285, P1286, P1441, P1514, P1515, P1516, P1517, or P1518 are not set. |
• | The intake air temperature (IAT) is more than -15°C (+5°F), but less than 75°C (167°F). |
• | The barometric pressure (BARO) is more than 74 kPa (10.7 psi). |
• | The engine is operating. |
• | The engine coolant temperature (ECT) is more than 70°C (158°F), but less than 120°C (248°F). |
• | Since the end of the last idle period, the engine speed is more than 900 RPM for a minimum of: |
- | 20 seconds for manual transmissions |
- | 30 seconds for automatic transmissions |
• | The closed loop fuel control is enabled. |
The PCM determines if oxygen storage capability of the catalytic converter has degraded to less than a calibrated threshold.
• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Clear the MIL and the DTC with a scan tool. |
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Yes | No | ||||||||||||||||||||||||||
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1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |||||||||||||||||||||||||||
2 | Are any other DTCs set? | Go to the applicable DTC table | Go to Step 3 | ||||||||||||||||||||||||||
3 | Check for the following conditions:
Did you find and correct the condition? | Go to Step 5 | Go to Step 4 | ||||||||||||||||||||||||||
Replace the catalytic converter. Refer to Catalytic Converter Replacement in Engine Exhaust. Did you complete the replacement? | Go to Step 5 | -- | |||||||||||||||||||||||||||
5 |
Does the DTC run and pass? | Go to Step 6 | Go to Step 2 | ||||||||||||||||||||||||||
6 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK |