Catalytic Converters Don’t Fail on Their Own!

It is Important to Check the Following Prior to Converter Replacement:

1) Retrieve and Repair All PCM Trouble Codes, Check for any Available TSBs or PCM Re-flash Updates

Any condition that increases emissions or affects sensor readings could cause a converter to fail diagnostics even if the converter is good.

• Many OBDII trouble codes will affect converter performance. Correct all other codes prior to correcting converter codes.

Re-flashing is the process of updating the PCM with the latest program available from the vehicle’s manufacturer.

• In some cases, manufacturers have released Technical Service Bulletins indicating that a re-flash
  of the PCM will help resolve emissions problems.

2) Correct Exhaust System and Vacumm Leaks

Leaks in the exhaust system can affect 02 (Oxygen) storage in the converter and lead to
improper O2 (Oxygen) Sensor readings, affecting the AFR (Air/Fuel Ratio) balance.

• Check all weld areas for cracks, especially O2 sensor ports.
• Check all pipe connections for improper alignment or burnt gaskets.
• Check all clamp connections for leaks.
• Pay close attention to any flex-pipe in the system.
• Check all of the small rubber vacumm hoses under the hood…pay close attention for cracked or split areas.

3) Make Sure Vehicle is in Proper Fuel Control

O2 (Oxygen) Sensors are critical to fuel control and to the PCM’s converter diagnostics.

• Check O2 Sensor operation to ensure vehicle is in fuel control. On most applications, the front O2 Sensor should be switching around 450 mv and the rear O2 Sensor should be above or equal to 450 mv, typically 650 – 850 mv. If the rear O2 sensor is not above or equal to 450 mv, check the vehicle’s emissions with a 4- or 5-gas analyzer. The front AFR sensors should indicate AFR of 14.7:1 under most conditions.
• Many diagnostic tools exist to accurately test O2 Sensors. Verify operation before replacing any sensors.

4) Test for Contamination

Converter poisoning occurs when the converter is exposed to substances that coat its working surfaces, enveloping the
catalyst to the point it cannot contact and treat the exhaust.

• An internal leak in the cooling system would allow coolant to enter the exhaust system and poison the catalytic
  converter.

-Perform a leak-down test to make sure the cooling system holds system pressure (check pressure cap for exact
pressure) for 15 minutes.

• Test for contaminated fuel or additives (E85, diesel).
• Check for excessive oil consumption (burning oil).
• High-mileage engines can have many mechanical problems that contribute to contamination.

-Perform a compression check to identify the condition of the piston rings, valve train, and combustion chambers.