Code 140

My 2001 3.8 Grand Prix Has A Check Engine Code Of Po 140. I Have Replaced The O2 Sensor But It Did Not Help. Any Ideas?

Welcome to AF.

Which 02 sensor did you replace? DTC P0140 refers to Bank 1, Sensor 2 position meaning the 02 sensor after the CAT convertor.

The O2 sensor that was replaced was after the cat. I ran the obd2 on the car again today. I now am getting a PO 420 code.

The O2 sensor that was replaced was after the cat. I ran the obd2 on the car again today. I now am getting a PO 420 code.

The rear 02 sensor is working since it is capable of monitoring the CAT and even generate a P0420 DTC. Therefore, bad CAT convertor!!!!!

2001 - 2002 GPs were deliverd with flaky CATs and it is a common problem. GM extended the warranty on them to 10 years or 120K miles.

How many miles do you have?

The car has 106,000 miles. How do I go about getting it replaced?

The car has 106,000 miles. How do I go about getting it replaced?

Print out the notice below. Call Pontiac Customer Service or a local GM/Pontiac dealer and let them know of your problem. It looks like you will qualify. It will be free of charge and under the extended CAT warranty. Good luck!


This is a special policy that raises warranty coverages on the converter in case you experience a failure.

Dear General Motors Customer:

As the owner of a 2001-02 Chevrolet Impala, Monte Carlo; Pontiac Grand Prix; or Buick Regal model vehicle, equipped with a 3.4L or 3.8L V6 engine, your satisfaction with our product is very important to us.

This letter is intended to make you aware that some 2001-02 Chevrolet Impala, Monte Carlo; Pontiac Grand Prix; and Buick Regal model vehicles, equipped with a 3.4L or 3.8L V6 engine, may have a condition where the catalytic converter is replaced due to complaints of lack of power or illumination of the Malfunction Indicator Lamp (MIL). This may be due to the front endcone insulation from the catalytic converter breaking away and blocking the front of the first catalyst brick and preventing the free flow of exhaust gas through the converter.

This is not a recall. Do not take your vehicle to your GM dealer as a result of this letter unless you believe that your vehicle has the condition as described above.

What We Have Done
General Motors is providing owners with additional protection for the Catalytic Converter. If this condition occurs on your 2001-02 Chevrolet Impala, Monte Carlo; Pontiac Grand Prix; or Buick Regal model vehicle, equipped with a 3.4L or 3.8L V6 engine, within 10 years of the date your vehicle was originally placed in service or 120,000 miles (190,000 km), whichever occurs first, the condition will be repaired for you at no charge .

What You Should Do
Repairs and adjustments qualifying under this special coverage must be performed by a General Motors dealer. You may want to call the service department at your dealer to find out how long they will need to have your vehicle so that you may schedule the appointment at a time that is convenient for you. This will also allow your dealer to order parts if they are not already in stock. Keep this letter with your other important glove box literature for future reference.

Thanks for the Info. I called the dealer and they are replacing it Monday.
Thanks again!!!!!!