P0430

DTC P0430

DTC DESCRIPTOR

DTC P0430
Catalyst System Low Efficiency Bank 2

DIAGNOSTIC FAULT INFORMATION
Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
A 3-way catalytic (TWC) converter controls emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The catalyst within the converter promotes a chemical reaction which oxidizes the HC and the CO that are present in the exhaust gas. This process converts the HC and the CO into water vapor and carbon dioxide (CO2), and reduces the NOx, converting the NOx into nitrogen. The catalytic converter also stores oxygen. The engine control module (ECM) monitors this process by using a heated oxygen sensor (HO2S) that is in the exhaust stream after the TWC. This HO2S 2, also referred to as the catalyst monitor sensor, 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 allowing the catalyst to heat, then wait for a stabilization period while the engine is idling. The ECM then adds and removes fuel while monitoring the HO2S 2. When the catalyst is functioning properly, the HO2S 2 response to the extra fuel is slow compared to the response of the HO2S 1, which is located before the TWC. When the HO2S 2 response is near that of the HO2S 1, the oxygen storage capability and efficiency of the catalyst may be degraded below an acceptable threshold. If the ECM detects the degraded condition, DTC P0430 sets.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0050, P0056, P0059, P0060, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0128, P0151, P0152, P0153, P0154, P0155, P0156, P0157, P0158, P0160, P0161, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0300, P0325, P0327, P0332, P0335, P0336, P0340, P0341, P0442, P0443, P0446, P0449, P0455, P0496, P0506, P0507, P1153, P1258, P1516, P2101, P2119, P2120, P2125, P2135, P2138, P2A03, P2A04, U0107 are not set.
- The engine has been running for more than 10 minutes.
- The engine speed is within 200 RPM of the desired idle.
- The engine coolant temperature (ECT) is between 75-126°C (167-259°F).
- The barometric pressure (BARO) is more than 74 kPa.
- The vehicle is in Closed Loop.
- The intake air temperature (IAT) is between -7 and +100°C (+19 and +212°F).
- The battery voltage is more than 10.7 volts.
- The throttle position (TP) is 1.5 percent or less.
- The short term fuel trim (FT) is between -10 and +10 percent.
- The engine load must be stable.
- Warm the catalyst by performing the following procedures:
- Fully open the hood.
- Place the transaxle in PARK for automatic transaxle.
- Place the transaxle is NEUTRAL for manual transaxle, with clutch pedal depressed.
- Set the parking brake.
- Press and hold the service brake.
- This diagnostic attempts 1 test during each valid idle period once the above conditions have been met for 5 seconds. This diagnostic attempts up to 6 tests during each drive cycle. The first test may be run after the initial warm up period of 10 minutes. Maintain engine speed between 2,000-3,000 RPM in Park or Neutral for 2 minutes. Allow the engine to return to a stabilized idle. Shift into drive for an automatic transmission, without touching the accelerator in order for the test to run. Between each subsequent test, maintain engine speed between 2,000-3,000 RPM in Park or Neutral for 2 minutes. Allow the engine to return to a stabilized idle. Shift into drive for an automatic transmission, without touching the accelerator in order for the test to run.
- Test the catalyst by performing the following procedures: Idle the engine and place the vehicle in Drive, or depress the clutch pedal for a manual transmission vehicle, to activate the diagnostic. Within 60 seconds, the air fuel ratio will transition lean for up to 7 seconds, and then may transition rich for up to 7 seconds.
- Verify if DTC P0430 has passed or failed this ignition cycle with the scan tool.

CONDITIONS FOR SETTING THE DTC
The ECM determines that the efficiency of the catalyst has degraded below a calibrated threshold. This diagnostic may conclude.

ACTION TAKEN WHEN THE DTC SETS
- 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.

CONDITIONS FOR CLEARING THE MIL/DTC
- 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.

DIAGNOSTIC AIDS
- These conditions may cause a catalytic converter to degrade. Inspect for the following conditions:
- 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
- The catalyst test may abort if the vehicle falls outside the conditions for running the DTC.
- The catalyst test may abort due to a change in engine load such as the A/C or engine cooling fan cycling.
- If 18 tests have been attempted, and the DTC has not run or passed during this key cycle, turn the key to OFF for 30 seconds. Perform the conditions for running A second time.
- If an intermittent condition cannot be duplicated, the information included in the Freeze Frame/Failure Records can be useful in determining the vehicle operating conditions when the DTC was set.
- The catalyst may have been temporarily contaminated with a chemical from a fuel additive, fuel contamination, or any of the above conditions.

CAUTION: Refer to Road Test Caution.

IMPORTANT: A new catalyst may fail this test due to out-gassing of the internal matting. If this occurs, operate the vehicle at highway speeds for approximately one hour and retest.

- If the condition is determined to be intermittent, refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics

CIRCUIT/SYSTEM TESTING

NOTE:
- Refer to Heated Oxygen Sensor (HO2S) Resistance Learn Reset Notice.
- Refer to Three-Way Catalytic Converter Damage Notice.

1. With the engine in closed loop and at operating temperature, increase the engine speed to 1,500 RPM for 1 minute and then return to stabilized idle. Is the HO2S 2 voltage parameter as active as the HO2S 1 voltage parameter?
- If it is as active then proceed with Circuit/System Testing.
2. Inspect the catalytic converter for the following conditions:
- Dents
- A severe discoloration caused by excessive temperatures
- Road damage
- An internal rattle caused by damaged catalyst substrate
- Restrictions
- If a condition is found, then replace the catalytic converter.
3. Inspect the exhaust system for the following conditions:
- Leaks
- Physical damage
- Loose or missing hardware
- Properly torqued HO2S
- If a condition is found, then replace the exhaust system.
4. Inspect the HO2S 2 for the following conditions:
- Grounded wiring harness
- Damage
- If a condition is found then replace the HO2S 2.
- If no physical condition is detected and the HO2S 2 is as active as the HO2S 1 after operating the engine at 1,500 RPM for 1 minute and then returning to a stabilized idle, then replace the catalytic converter.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Exhaust Manifold Replacement - Left (3.5L) Exhaust Manifold Replacement - Left (3.9L)
- Catalytic Converter Replacement - Left (3.5L) Catalytic Converter Replacement - Left (3.9L)
- Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 2
- Exhaust Leakage
- Restricted Exhaust Verification Tests

REPAIR VERIFICATION
1. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. 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.
- If this DTC resets, repeat this procedure.
- If this DTC does not reset but others do, perform those diagnostics.