Repair or sell?

[dmerle]

Yes! But, financially it does make more sense to keep the car

[Mustangman]

@dmerle1

financially it does make more sense to keep the car

Only you can determine that. There is no universal rule that everyone uses to decide when a car is “done.” In fact there are folks that search for cars like this - the little old lady car - to buy and drive because they are cheap transportation. They buy cars the owner knows are in need of repair and they negotiate an extra low price and go fix the car themselves or take it to their budget independent mechanic to repair. You can be that guy, or you can sell to that guy, your choice.

[Cavell]

[the_same_mountainbike]

@Whitey

From a strict financial standpoint, this car is worth less than $1,500, so the rational financial choice (if you can afford a replacement car) based on the math is to not spend more than the car is worth to fix it.

If it were my car, though, I’d probably fix it,

That’s why I’ve long believed that the value of a car to its owner is far higher than the published value of the car on the used car market. Straight monetary calculations do not reflect the costs of replacing the car.

[Mustangman]

Agree with @the_same_mountainbik What if you don’t have more than $1500 to use on this or any car?

If you sell the car with a CEL on, you won’t get the $1500 book value. Maybe you’ll get $750. If you spend the $1500 on the car, the question you have to ask yourself; How good a car can I get with $2250 I’d have if I didn’t fix this one? The answer; you’ll get a completely unknown $2250 car that could cost you another $1500 in 6 weeks or 6 months. More risk.

[George_San_Jose1]

@dmerle1

It is showing a P0420 code (which keeps coming back after I clear it (with my ScanGauge

That’s the code for a potentially faulty cat, but it doesn’t necessarily mean the cat is the problem. Take a look at the post by Tester below which shows how the computer compares the pre-cat O2 sensor signal to the post-cat O2 sensor signal. You need to make sure that same test has been done on your cat, and it shows the cat is bad, and not some other problem, like a bad or disconnected O2 sensor.

Has my Catalytic Converter gone bad and is it worth it to replace it?

p0420 is reduced catalyst efficiency - that doesn’t always means the cat is bad, especially when you have a misfire. P0502 is the vehicle speed sensor which should have no effect on misfires.problem or take it to So to answer your questions, Yes, use a pressure tap into the forward O2 sensor and run the engine open loop to check backpressure You have several places to insert the pressure taps, test, and decide which cat is clogged, if, in fact, they are. No, this is time for you to properly …

[dmerle]

Thanks for this info. I have a ScanGauge on this car. If, as a rough DIY test, I set it up to read the O2 sensors, will I be able to get the same info by watching the outputs – the pre-cat one will fluctuate and the post-cat should be fairly steady? Or will this be useless if one of the sensors is the problem?

[George_San_Jose1]

You can only do that test by observing the sensor’s voltage vs time graphs as shown in Tester’s post. If your scan tool has that capability to display the graphs – most of the inexpensive ones don’t – then you should be able to get a good idea if the cat is actually the problem by looking at those two waveforms and comparing them to Tester’s graphics post.

[irlandes]

Yes, we have had many discussions on this board on cats being replaced when they were not bad. There are mechanics who insist that when you get a P0420 it ALWAYS means the cat is bad. Due to the high cost of a cat, see if you can find a mechanic like our db4690 who can use a graphing scanner and see the sensor outputs for certain. Only then let them put on an expensive cat.

Of course, if you can get a cat as stated her for under $300 it might be the best way to go.

My 2002 Sienna had several P0420 codes over its 220,000 miles and in every case replacing the sensors fixed it.