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• | 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. |
A 3-way catalyst controls emissions of hydrocarbons, CO and NOX. The catalyst within the converter promotes a chemical reaction, which oxidises the hydrocarbon(s) and the CO that are present in the exhaust gas. This process converts the hydrocarbon(s) and the CO into water vapor and CO2, and reduces the NOX, converting the NOX into nitrogen. The catalyst also stores oxygen. The ECM monitors this process by using heated oxygen sensors (HO2S) that are in the exhaust stream before and after the 3- way catalyst. The HO2S produces an output signal that the ECM uses to calculate the oxygen storage capacity of the catalyst. This indicates the ability of the catalyst to convert the exhaust emissions efficiently. The ECM monitors the efficiency of the catalyst by monitoring the HO2S during an off-idle, ECM commanded Decel Fuel Cut Off (DFCO) event. When the catalyst is functioning properly, the post catalyst HO2S response to the fuel conditions during the DFCO event is slow compared to the response of the pre catalyst HO2S. When the post HO2S response is near that of the pre HO2S, the oxygen storage capability and efficiency of the catalyst may be degraded below an acceptable threshold.
• | DTC P0030, P0036, P0053, P0054, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P013A, P013B, P013E, P013F, P0140, P0141, P0171, P0172, P0178, P0179, P0201, P0202, P0203, P0204, P0222, P0223, P0300, P0301, P0302, P0303, P0304, P1133, P16F3, P2101, P2135, P2269, P2270, P2271, or P2A00 is not set. |
• | The engine speed is between 1,800-3,500 RPM to enable the catalyst diagnostic. Once the engine speed is in range, the engine speed must be between 1,700-3,650 RPM to keep the test enabled. |
• | The accelerator pedal position is less than 100 %. |
• | The evaporative emission (EVAP) purge is not commanded ON. |
• | The HO2S heaters are ON for greater than 60 s. |
• | The air flow into the engine is between 18-28 g/s. |
• | The system voltage is between 10-32 V. |
• | The vehicle speed is between 40-145 km/h (25-90 MPH) to enable the catalyst diagnostic. To keep the test enabled the vehicle speed cannot change greater than 5 km/h (3 MPH). |
• | The catalyst calculated temperature is less than 1,000°C (1,832°F). |
• | The engine is operating in closed loop. |
• | The engine is operating in Decel Fuel Cut Off (DFCO). |
This diagnostic attempts one test during each valid OFF-idle period once the above conditions have been met. This diagnostic attempts up to 6 tests during each drive cycle.
The ECM determines that the efficiency of the catalyst has degraded below a calibrated threshold.
DTC P0420 is a Type A DTC.
DTC P0420 is a Type A DTC.
Inspect for the following conditions, which may cause a catalyst to degrade:
• | An engine misfire |
• | High engine oil or high coolant consumption |
• | Retarded spark timing |
• | A weak or poor spark |
• | A lean fuel mixture |
• | A rich fuel mixture |
• | A damaged oxygen sensor or wiring harness |
Hybrid Modes of Operation Description
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
⇒ | If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis. |
⇒ | If not the specified value, operate the vehicle within the Conditions for Running the DTC. |
⇒ | If no decision has been made, repeat steps 2-4 until the Test Result parameter indicates Pass or Fail. |
• | Dents |
• | A severe discolouration caused by excessive temperatures |
• | Road damage |
• | An internal rattle caused by damaged catalyst substrate |
• | Restrictions |
⇒ | If a condition is found, replace the catalytic converter. |
• | Leaks |
• | Physical damage |
• | Loose or missing hardware |
⇒ | If a condition is found, repair the exhaust system. |
• | The HO2S is not at the correct torque |
• | Damage |
⇒ | If a condition is found, repair or replace the B52B Heated Oxygen Sensor 2 as necessary. |
⇒ | If not the specified value, operate the vehicle within the Conditions for Running the DTC. |
⇒ | If no decision has been made, repeat steps 5-7 until the Test Result parameter indicates Pass or Fail. |
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