P0430

DTC P0430

DTC DESCRIPTOR

DTC P0430
Catalyst System Low Efficiency Bank 2

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, P0174, P0175, 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 5 minutes.
- Since new, the vehicle must have run for at least 1 hour, followed by a key cycle.
- The engine coolant temperature (ECT) is between 70-123°C (158-253°F).
- The barometric pressure (BARO) is more than 70 kPa.
- The vehicle is in Closed Loop.
- The intake air temperature (IAT) is between -20 and +250°C (-4 and +482°F).
- The battery voltage is more than 10.7 volts.
- The throttle position (TP) is 2 percent or less.
- The short term fuel trim (FT) is between -10 and +10 percent.
- The calculated mass air flow (MAF) is between 4-16 g/s, 4.5-16 g/s for manual transmission vehicles.
- The engine speed is less than 1,100 RPM.
- The predicted maximum TWC temperature for the applicable bank is less than 840°C (1,544°F). 850°C (1,562°F) for manual transmission vehicles.
- Idle the engine and keep the vehicle in Drive, or depress the clutch pedal for a manual transmission vehicle to activate the diagnostic. Within 20 seconds the air fuel ratio will transition rich, short term fuel trim may change to approximately 16 percent, for up to approximately 7 seconds. Then, it may transition lean, short term fuel trim may change to approximately -16 percent, for up to about 5 seconds.
- Verify if DTC P0430 has passed or failed this ignition cycle with the scan tool.
- This diagnostic attempts one test during each valid idle period when the above conditions have been met. This diagnostic attempts 6 tests during each drive cycle.

CONDITIONS FOR SETTING THE DTC
- The ECM determines that the efficiency of the catalyst has degraded below a calibrated threshold.
- This diagnostic may conclude in as few as one test attempt. However, this diagnostic may require as many as 18 test attempts, which would require at least 3 drive cycles. Each test attempt may conclude within approximately 3 minutes, 2 minutes for manual transmission vehicles.

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
- Inspect for the following conditions, which may cause a TWC 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
- The catalyst test may abort if the vehicle falls outside the conditions for running the DTC.
- A catalyst may be temporarily degraded or contaminated for the following reasons:
- Use of fuel with high sulfur content
- A chemical from a fuel additive
- Fuel contamination
- If any of the above conditions exist, then drive the vehicle between 88 and 96 km/h (55 and 60 mph) for 10 minutes and retest the converter.

CAUTION: Refer to Road Test Caution.

- If 18 tests have been attempted and the DTC has not run or passed during this key cycle, turn the key OFF for 30 seconds. Perform the conditions for running a second time.
- After a code clear, the catalyst test will run once if the test is a pass. Allow the engine to return to a stabilized idle. Keep the vehicle in Drive.

IMPORTANT: DO NOT touch the accelerator while a catalyst test is in progress.

- If an intermittent condition cannot be duplicated, the information included in the Freeze Frame Records can be useful in determining the vehicle operating conditions when the DTC was set.
- 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.

IMPORTANT: A new converter with less than 100 miles on it may set P0430 due to out-gassing of the internal matting. Operating the vehicle at highway speeds for approximately 1 hour may correct the condition.

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.
- If the applicable HO2S 2 voltage parameter is as active as the applicable HO2S 1 voltage parameter, then proceed with Circuit/System Testing.
2. Inspect the applicable 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 applicable catalytic converter.
3. Inspect the exhaust system for the following conditions:
- Leaks
- Physical damage
- Loose or missing hardware
- Properly torqued all applicable HO2S
- If a condition is found, then repair the exhaust system.
4. Inspect the applicable HO2S 2 for the following conditions:
- Grounded wiring harness
- Damage
- If a condition is found then replace the applicable HO2S 2.
- If no physical condition is detected and the applicable HO2S 2 is as active as the applicable HO2S 1 after operating the engine at 1,500 RPM for 1 minute and then returning to a stabilized idle, then replace the applicable catalytic converter.

REPAIR INSTRUCTIONS

IMPORTANT:
- Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
- A new converter with less than 100 miles on it may set P0430 due to out-gassing of the internal matting. Operating the vehicle at highway speeds for approximately one hour may correct the condition.
- Exhaust Manifold Replacement (2.2L Engine)
- Catalytic Converter Replacement (3.5L Engine - Front) Catalytic Converter Replacement (3.5L Engine - Rear) Catalytic Converter Replacement (3.9L Engine - Front) Catalytic Converter Replacement (3.9L Engine - Rear)
- Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 2
- Exhaust Leakage
- Restricted Exhaust