Driving around with a CEL... Bad idea?

So my 2001 3.4L (161000mi) has had the Check engine light on for over a year now due to code P0420 (Cat efficiency bank 1) and a few months ago i replaced the battery which reset temporarily erased the code. I smogged it immediately after that and it passed. The technician said it was about half way to failing, so to me that means im just going to wait 2 more years to replace the cats. Will it hurt the engine driving with a po420 code?

 

sure wont help it

 

I wont help but it shouldnt hurt anything either.

 

You drove around with the CEL on for a year?



It could be an O2 sensor or the CAT itself.

If you don't fix the problem - the truck won't run as good as it should. Your gas mileage will probably suffer and maybe someone else knows the results from long-term 'inefficiency' of the engine.

Do you really want to take that chance? The amount of money & time you've already put (smog test) into it...you could've learned how to fix this yourself, had parts ordered already.

 

Same thing here.
It's hard to say what the real problem is.
A small exhaust leak caused my problems for about a year. The code is just indicating a discrepancy between the 2 readings.

So, even though the O2 sensor(s) are between 100-200 dollars... It'd be nice to know what is really the problem.

 

My code P0420 was just an exhaust gasket that needed to be replaced.

 

Ok so here's an update. My technician buddy used his fancy SNAP-ON computer diagnostic thing and long story short, my cats are close to dead, they are working enough for me to pass smog but they are taking waaaay to long to warm up and when they finally do they are working at half the capacity they should be. (thats what he told me anyway) BUT! here's a twist: the truck threw the code p0171 (lean condition bank 1) my guess would be the MAF needs to be cleaned. But would driving with blown cats hurt anything? (other than california's air quality )

 

Keep me updated cmack! Ill see if cleaning the MAF sensor fixes it...

 

Hey here's something interesting, I decided to change the spark plugs today and found Denso plugs on the driver side, and NGK on the other side...which I believe that these were the original plugs from the factory. Keep in mind my truck has 161,xxx miles on it. This is what they looked like...






Pretty bad huh. The Denso's look especially bad. I measured the gap between the electrode and the ground to be about .05 inches on each. Just put in the new factory plugs and it made a dramatic difference in power! Moral of the story: don't do drugs and check your plugs if you haven't already.

 

The cats went out on my '00 Taco a few years ago. I drove around for about 3 years with the light on because I wasnt goin to fork over $900 a piece from the stealership for the 2 cats. To the naked eye it didnt hurt anything. I still managed 21-23 mpg's highway. I found both cats made by Walker for approx $375 at NAPA. Replaced cats and a/f sensor and all was well. I would check all the cheaper fixes first...a/f, o2, maf sensors and exhaust leaks. Plus everyone one on here offers pretty accurate advice. I usually check here before a mechanic or the stealership!!