HI guys, I'm new to the forum and the Corvette world, so I hope you can help me out. Just bought an 01 Coupe a few weeks ago, last week I got a code P0430, I replaced both sensors on the passenger side. Went for a ride, about 75 miles and the same code popped up. Now I'm worried, what do I have to replace next. Any help will be greatly appreciated.

 

You need to take it to a tuner and have those codes ignored.

Depending upon the age of your car, the cats may be under warranty. If so, have the stealership put new cats in it instead.

 

I would focus more on troubleshooting....not what to replace.

 

FYI... P0430 is for catalyst inefficiency. The only two causes of it that I'm aware of (without other codes) is an inefficient cat or inaccurate 02 sensors.

 

Since the OP just purchased the car, I consider it condition unknown. Who knows if there were headers on the car before, etc. Flaky wiring to the O2 or an exhaust leak can throw the same code.

 

Does the car have a stock exhaust? If it has high-flow cats, you may get these codes. They are easy to turn off.

 

Here is the theory of operation and the diagnostic procedure to follow:
DTC P0430 Catalyst System Low Efficiency Bank 2

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. 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 PCM monitors this process using Bank 2 HO2S #2. Bank 2 HO2S #2, located in the exhaust stream past the three-way catalytic converter, 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 three-way catalytic converters oxygen storage capacity is below a threshold considered acceptable.



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

1. The PCM captures the current rear HO2S rich/lean status.
2. The Air Fuel ratio transitions from rich to lean or lean to rich depending on the capture rear HO2S rich/lean status.
3. The Air Fuel ratio transitions a second time opposite the first Air Fuel ratio transition.
4. 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 Heated Oxygen sensors when the Air Fuel ratio transitions occurred.
5. 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 DTC sets if the time exceeds a predetermined threshold.

Conditions for Running the DTC

• No AIR, CKP, CMP, IAT, IC, MAF, MAP, ECT, TP, EVAP, Right Bank HO2S, Misfire, Right Bank Fuel Trim, Injector, VSS, Engine Protection, or Transmission DTCs are set.
• The engine is operating.
• The ECT is greater than 65°C (149°F).
• The vehicle speed is less than 136 km/h (85 mph).
• The throttle angle is greater than 10%.
• The engine speed is less than 4000 RPM.
• The MAP is between 25 kPa and 80 kPa.
• The air flow is between 14 gm/s and 40 gm/s.
• The closed loop fuel control is enabled.

Conditions for Setting the DTC


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

Action Taken When the DTC Sets

• The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

• The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Use a scan tool in order to clear the MIL and the DTC.

Test Description




The numbers below refer to the step numbers on the diagnostic table.
Step 4. Before replacing the Three Way Catalytic Converter, correct any conditions which may have damaged the catalyst.

Step

Action
Value(s)
Yes
No

Step 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

Step 2
Are any other DTCs set?
--
Go to the applicable DTC table
Go to Step 3

Step 3



Check for the following conditions:

• Verify that the three-way catalytic converter is an original equipment part.
• Inspect the three-way catalytic converter for damage (dents, severe discoloration caused by excessive temperature, holes, etc.).
• Insure that the internal three-way catalytic converter rattle caused by damaged catalyst is not present.
• Inspect the exhaust system for leaks, damage, or loose or missing hardware (area from converter to HO2S #2 primarily).
• Insure that the HO2S #1 and the HO2S #2 are secure and that the 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

Step 4
Replace the catalytic converter. Refer to Intermediate Pipe Replacement in Engine Exhaust.
Is the action complete?
--
Go to Step 5
--


Step 5

1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
2. Idle the engine at the normal operating temperature.
3. Select the Diagnostic Trouble Code (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

Step 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



Bill