CEL woe's (1 Viewer)

[liljlandon]

Gents,

My CEL pops up and says I have a bad sensor bank 1. I replaced the frontal most o2 sensor. CEL stayed off for about 150 miles. Came back on, so I pulled the code. Same thing. I erased the code, and its done it twice again. Around 120, and now at about 230.

Is my new 02 sensor bad? With the old one, if I erased it it lasted about 30-40 miles before it popped back on.

Could it be a starting-to-plug cat? What would happen if I removed the cat and straight piped to the muffler? Thats how my mini's ran...

I don't have emission laws worth enforcing locally, so I doubt it would create a known legal issue

EDIT: Now the code is P0420 Low efficient catalyst bank 1

 

[liljlandon]

To answer my own question...

It's not the 02 sensor, its the cat being 'plugged' to cause this code "P0420 Catalyst System Efficiency Below Threshold (Bank 1" to appear. Replacing the 02 sensor will do nothing, so I may have wasted the 120.00 bucks for it. Go figure.

However, if you pull the cat, it makes this worse because now there is no cat efficiency. Damn. I hate emission laws

 

[liljlandon]

And to make this easier for people who may have this happen;
This is the cheapest method of replacing the bank one cat. YOU WILL HAVE TO WELD IT IN!
Amazon.com: Magnaflow 91075 Universal Catalytic Converter (Non CARB compliant): Automotive

 

[raydouble]

At a hundred fifty thousand miles it was only a matter of time on that front A/F sensor. I wouldn't feel too terrible about spending the cash on it.

 

[TheDurk]

Your rear O2 sensor can cause a P0420 without throwing another code. I'd sure try that (if it's old) before going to a new cat that won't be as good as your factory cat. I was getting P0420 in March of '09 with 113K on my original rear o2(no other code) and swapped it for a new Denso. No P0420's since--now at 134K. If the front one was bad, the rear is usually pretty close, too.

 

[liljlandon]

For reference- Buy the bolt in replacement. That was a fxxxing nightmare and a half. I traced the old one out on a cardboard and made sure i had exact measurements/angles so my custom one would fit exact.

First problem- Removing old manifold nuts. THAT was horrible. Had to remove two with creativity, the first one came right off after it was broken loose, the others got maulled up in the process of breaking them loose.

Second Problem- Welding with an unfamiliar welder. I loaned my MIG to my uncle about 180 miles away. I borrowed my dads, which is a 110V. Welds nothing like my 220V. The biggest issue was, with only 4 heat adjustments, 2 was too cold and 3 blew through. Its welded with no leaks though.

Third problem - I tacked everything and then test fit. It worked out fine in the test. I welded it up, and some how I pulled the flange 1/4" to the bottom. I had the room to adjust with about a 1/2" forward or backward warp, but not an angled warp. Had to cut out a bout 8" of exhaust and replace with a flexible one to get the angle. Now I noticed the flexible hose allows the exhaust to move and when hitting bumps at high speed (cause I've got 100's of miles worth of unpaved roads and all )it rubs the trans mount.

Best solution - Get a longer flex hose, remove about 2" worth of pipe in the down tube of the cat.
Benefits- Prevent rubbing and gain ~1" of ground clearance at the cat while maintaining safe amount of space between body and cat.

 

[liljlandon]

Your rear O2 sensor can cause a P0420 without throwing another code. I'd sure try that (if it's old) before going to a new cat that won't be as good as your factory cat. I was getting P0420 in March of '09 with 113K on my original rear o2(no other code) and swapped it for a new Denso. No P0420's since--now at 134K. If the front one was bad, the rear is usually pretty close, too.

Ill end up replacing it when budget allows. I haven't thrown the code again *yet* with about 140 miles on the new setup. Which is the longest its been without the code for a while. Also, I gained about 2mpg out of half a tank. Which sure as hell helps my pocket book.

 

[ken_79-fj40]

My 4runner had been throwing catalyst efficiency codes a few times a year. Last year I replaced the rear sensor and cut the flange off the old one to make a spacer and installed it spacing the new sensor out of the exhaust stream a little. Didn't see the code again for almost a year. It's out again and as long as it stays out through inspection later this month I'm golden for another year. I know it needs a cat but it runs fine. Oh and the cheap Magnaflow cats suck. You'll probably be changing that out before long.

 

[liljlandon]

My 4runner had been throwing catalyst efficiency codes a few times a year. Last year I replaced the rear sensor and cut the flange off the old one to make a spacer and installed it spacing the new sensor out of the exhaust stream a little. Didn't see the code again for almost a year. It's out again and as long as it stays out through inspection later this month I'm golden for another year. I know it needs a cat but it runs fine. Oh and the cheap Magnaflow cats suck. You'll probably be changing that out before long.

It was 75 bucks.

At about 300 miles. No light! Runs better than it did before, and I would know since I drive it more than i care to admit!