Check engine light after frame replacement?

Oh yeah, almost forgot, Sachou, I found this website:

http://www.p0420.com/

Limited but helps a little with our common code. If I did replace the cat, any suggestions for brand? Place to buy it? Tips for installation?

 

This can't be right, a toyota OEM cat cost $700-$800?????

 

No, it doesn't feel bad at all, if the light wasn't on I probably wouldn't know anything was wrong. The only thing I've noticed is the mpg has gone down a little, but I thought that was due to winter gas mix. I guess if I replaced the O2 sensor(s) it wouldn't be a waste no matter because they will eventually go bad anyway.

 

im gonna say, im 99% sure that its the upstream o2 sensor.

 

Yeah, that seems about right. Those things are pretty pricey...someone on this forum got theirs stolen a few weeks ago.

Doesn't really make sense to me, though, I see rednecks "gut" their cats all the time for more performance. Wouldn't that throw a major code?

And I've also seen highflow cats go for around a hundred bucks. Do these really work?

lol, there's an entire website dedicated to the code. Wow. Must be pretty common. Thanks.

Edit: Looks like Magnaflow makes one for around $150, not CA legal, though...Magnaflow seems rebutable to me, if it's an upgrade over stock, why would anybody pay $800 for an OEM, or even freaking steal one from somebody's car!?

 

Another question to maybe help narrow this down - what would be the most likely cause of a reduction in MPG? I had been getting about 300 miles before the low gas light comes on, the first tank of gas since the CEL is only about about 270 and its near empty. Could this be related to O2 sensors or the cat?

 

x3.......mine went out a few months ago....couldnt tell of a mileage change since i changed it out that day...but bad o2 sensors will drop your mileage a good bit.

 

From some of the other posts I've read I'm glad I didn't take it to a shop and pay $100 for a diagnosis, seems like many people who do that still have the problem and need to buy other pieces to fix it anyway. Also from reading the shop manual, it seems like the first place to start with a P0420 is check for exhaust leaks, 2nd is check/replace the front O2 sensor (A/F sensor, whatever you want to call it). This might be a stupid question, but what's the best way, short of taking the whole exhaust off, to check for leaks? I know on my motorcycle the leaks sound like very loud ticking, will it be the same for the tacoma?

 

Yeah, I had that question too...then I thought, why not put a dye in the system or something so you can see the leak?

So I came up with seafoam, since I was about to do it anyways, and it's supposed to smoke a lot, so you might be able to spot a leak with it.

 

Finally had time to get underneath and yep, major leak between the rear of the back cat and the rest of the exhaust. I'm assuming when they replaced the frame they had to take the whole exhaust off, right? The 2 bolts connecting the cat to the rest of the exhaust where just finger tight, actually not even finger tight, I unscrewed both of them with just my fingers. So I tightened them both up as tight as I could make it without snapping the bolts, I didn't use a torque wrench, just cranked them tight.

IF this was the problem (leak between the cat and the 2nd O2 sensor) will the CEL correct itself, or do I need to reset it somehow? As for the O2 sensors, I was underneath with a flashlight and its obvious the front one is new, it's still shiny. The rear one is original as far as I know.

Final question: there is another smaller leak back by the muffler, between the muffler and the exhaust between the cat/rear O2 sensor. This wouldn't have any effect, would it? Since it's after the 2nd O2 sensor I don't think there's any way but just want to be sure.

 

Might wanna invest in some stainless steel nuts and bolts, and lock washers, so they won't loosen again.

You can always unplug the battery for about 15 minutes for the ecu to reset itself, but in my experience, the light should probably go away by itself if you fixed the problem.

Isn't anything behind the sensor not going to show up to the ecu? I thought I heard that somewhere...

 

If you found a huge leak, than that's where the P0420 code came from. The O2 sensor was missing a lot of exhaust going through it. Good thing you didn't go buy an $800.00 cat!