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Questions and Answers

Ford Aspire DTC P0420

Q. I have a 1997 Ford Aspire, automatic transmission and 90,000+ miles. I recently took it to get an inpsection done in Charlotte, North Carolina, which I didn't know required emissions testing. The car failed because it got a DTC P0420. The engine light is also not working. When I take my car to the mechanic, what should he tell me he'll have to do to the car? How much should I expect to pay?

Ford Aspire DTC P0420

A little history:
I was recently hit from behind by an SUV that knocked me into a pick up truck. The car sustained front and rear bumper and light damage which was fixed. I also recently had to get a new alternator. Any information you give me will be appreciated.


A. P0420 Catalyst System Efficiency Below Threshold (Bank 1) indicates the Three Way Catalytic Converter (TWC) is not working properly. The only remedy for this is to replace the TWC.

Most times it is an engine problem that causes the TWC to go bad. Problems like engine misfires, running too tich or excessive oil consumption. All of these things will need to be checked to insure everything is ritgh or you could wind up with another bad TWC.

If the Check Engine Light (MIL) doesn't come on with the key on and engine off (bulb check) the MIL bulb is probably burnt out. Or somebody removed the bulb rather than fix a problem.

Additional Information provided courtesy of ALLDATA

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