DTC P0430 Catalyst System Low Efficiency Bank 2. Oldsmobile Shelby Series 1 1999

For 1990-2009 cars

### Circuit Description

In order to maintain a reasonably low emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), the engine controls system uses a three-way catalytic converter (TWC). The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas. This reaction converts them into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting it to nitrogen. The powertrain control module (PCM) monitors this process using Bank 2 heated oxygen sensor (HO2S) #2. Bank 2 HO2S #2, located in the exhaust stream past the TWC, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to convert exhaust emissions effectively. If the catalyst is functioning correctly, the Bank 2 HO2S #2 signal will be far less active than that produced by Bank 2 HO2S #1. This indicates that the TWC oxygen storage capacity is below a threshold considered acceptable.

When the conditions for running this DTC are met, the following occurs:

• | The PCM captures the current rear HO2S rich/lean status.

• | The air fuel ratio transitions from rich to lean or lean to rich depending on the capture rear HO2S rich/lean status.

• | The air fuel ratio transitions a second time opposite the first air fuel ratio transition.

• | The PCM captures the response time,the time the HO2S goes from below 300 mV to above 600 mV and from 600 mV to below 300 mV, of the front and rear HO2S when the air fuel ratio transitions occurred.

• | The PCM measures the time it takes the rear HO2S voltage to cross a reference rich/lean threshold minus the time it takes the front HO2S voltage to cross the same rich/lean threshold. The time difference from the front and rear HO2S is the oxygen storage capacity of the catalyst. This diagnostic trouble code (DTC) sets if the time exceeds a predetermined threshold.

### Conditions for Running the DTC

• | DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0171, P0172, P0174, P0175, P0200, P0300, P0325, P0327, P0440, P0443, P0446, P0449, P0500, P0506, P0507, P0704, P1336, P1441, ignition control (IC) and HO2S DTCs are not set.

• | The engine is operating for longer than 400 seconds.

• | The engine coolant temperature (ECT) is between 80°C (176°F) 120°C (248°F).

• | The intake air temperature (IAT) is between -15°C (5°F) and +75°C (167°F).

• | Engine speed is more than 900 RPM for a minimum of 22 seconds since the end of the last idle test.

• | The barometric pressure (BARO) is more than 74 kPA.

• | The fuel system is operating in Closed Loop.

### Conditions for Setting the DTC

The PCM determines the oxygen storage capability of the catalytic converter has degraded below a calibrated threshold.

### Action Taken When the DTC Sets

• | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.

• | The malfunction indicator lamp (MIL) will not illuminate.

• | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

### Conditions for Clearing the DTC

• | A last test failed, or current DTC, clears when the diagnostic runs and does not fail.

• | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

• | Use a scan tool in order to clear the DTC.

### Diagnostic Aids

If the HO2S parameter is monitored using a scan tool while this diagnostic is running, the HO2S voltages may be fixed low or high.

### Test Description

The number below refers to the step number on the diagnostic table.

1. Before replacing the TWC, make sure that any conditions which may have caused the catalyst to be damaged have been corrected.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Are any other DTCs set? | -- | Go to the applicable DTC table | Go to Step 3

3

Inspect for the following conditions:

• | Verify that the TWC is an original equipment part.

• | Inspect the TWC for damage such as dents, severe discoloration caused by excessive temperature, holes, etc.

• | Insure that internal TWC rattle caused by damaged catalyst is not present.

• | Inspect exhaust system for leaks, damage, or loose or missing hardware in the area from the converter to the HO2S #2 primarily.

• | Insure that the HO2S #1 and the HO2S #2 are secure and that their pigtails and wiring are not damaged or contacting the exhaust.

Did you find and correct the condition?

--

Go to Step 5

Go to Step 4

4 | Replace the converter. Is the action complete? | -- | Go to Step 5 | --

5

1. Select the DTC option and the Clear DTC Information option using the scan tool.
2. Idle the engine at the normal operating temperature.
3. Select the DTC option and the Specific DTC option, then enter the DTC number using the scan tool.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 6

Go to Step 2

6 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK