Help! DIC Codes

[HillVette]

I have the DIC codes P0420 and P0430 and the GM dealership tells me that I probably have to change my two catalytic converters ! My 2000 auto only has 88000 km's or 55600 miles on it. Seems strange that the converters have gone bad already. Could it be something as the 02 sensor or EGR ? Any help or info would be much appreciated ! I also have the code B0338 Inside Air temp sensor open, should I be concerned with this code as I was told it had something to do with the air conditioning. Thanks again for your help !
Al

 

[HillVette]

By the way regarding those codes. It seems to me that I can smell something like raw fuel with the top off. Just thought this may help someone analysing this problem !

Al

 

[Toms007]

Al, I don't have my FSM here, but I would guess that someone will be along to help you out. GMJunkie is always a good source.

 

[gmjunkie]

My guess is cats too!!But you need to do some checking!
PO430 says basically the same thing only is bank #2 Right side!!
Cats are like electronics,they can go bad anytime!Just depends,lot of things can come into play,I've seen them last 2-300,000 miles,I've seen them last 20,000!



2000 Chevrolet/Geo Corvette
DTC P0420 Catalyst System Low Efficiency Bank 1

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 3-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 1 HO2S #2. Bank 1 HO2S #2, located in the exhaust stream past the 3-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 1 HO2S #2 signal will be far less active than that produced by Bank 1 HO2S #1. This indicates that the 3-way catalytic converters oxygen storage capacity is below a threshold considered acceptable.



The PCM performs this diagnostic at idle when the conditions for running this DTC are met, the following occurs:

1. 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 Heated Oxygen sensors when the Air Fuel ratio transitions occurred.
2. 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

• AIR, CKP, CMP, IAT, IC, MAF, MAP, ECT, TP, EVAP, Left Bank HO2S, Misfire, Left Bank Fuel Trim, Injector, VSS, Engine Protection, or Transmission DTCs are not set.
• The IAT is greater than -7°C (19°F), but less than 75°C (167°F).
• The BARO is greater than 74 kPa (10.7 psi).
• The engine is operating.
• The ECT is greater than 75°C (167°F), but less than 117°C (243°F).
• The engine speed is greater than 850 RPM for a minimum of 17 seconds for manual transmissions and 27 seconds for automatic transmissions since the end of the last idle period.
• The closed loop fuel control enabled.

Conditions for Setting the DTC

The PCM determines 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) when the diagnostic runs and fails.
• The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or 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.

1. Before replacing the Three Way Catalytic Converter, correct any conditions which may have damaged the catalyst.

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



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



5

1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.Start the engine and idle at the normal operating temperature.Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
2. 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

 

[jdeatsch]

I'm gonna sell my FSMs and just call Junkie from now on.

What a guy.

 

[gmjunkie]

I'm gonna sell my FSMs and just call Junkie from now on.

What a guy.

Only $3.99 a minute!

Yes,I accept Pay-Pal!!