Ok, well I've searched and done some reading. I see some of us have this CEL because of a clogged cat! I've also seen alot of guys saying just replace the sensor and see what happens.

I had the Magnaflow high flow cat installed, and about 20 miles down the road my CEL came on. Scanned and it came up with P0138. I cleared out with the scan tool and it came back within 10 miles.

They are a good exhaust shop but im pretty sure they didn't remove the negative break cable, Im going to try this and check all my wires, and report back.

Any thoughts, comments, or advice would be helpful. Seen alot of cat deletes or plugged cats, but none after the High Flow. Thanks guys!

 

I have heard that guys got the code because of the higher flow of the magnaflow cat. Some people in emissions states don't get magnaflow cats because of the error code that comes on.

What you can do is get an O2 simulator from www.thefastman.com or do the spark plug non fouler trick.

 

I have the magnaflow high flow cat on mine and am not having any problems. I did make the mistake of installing Bosch 02 sensors when I changed the Cat but so far still no problems, no codes, runs fine.

Larry

 

Have a magnaflow cat on mine, no problems. But a different exhaust shop told me they didn't install magnaflow cats for the very reason you mention. Maybe the bulb is out on my dash and I don't know it. Ignorance is bliss if my bulb's out, I guess.

 

Possibility the new cat is defective though...wonder if your shop would put another one on if you tell them you got that code?

 

The truck runs great, and actually mileage in town driving went up just a tad. Just wondering if they didnt mess up the sensor when they installed them. I also bought the cat on my own and had them install it, I kinda doubt the cat would be bad. Its not idling rough or lags on power. I'll check the wires and stuff after work.

I also live in North Dakota so there is no worries about inspection here.

 

If it runs good I'd jump on eBay and order me an O2 blank kit they're like $5 and you just install it between the exhaust and O2 and the truck thinks its all flowing normal. Did this on the mustang after I punched out the clogged cats and haven't got a cel from O2s since

 

The shop that told me the magnaflow's sometimes set codes also told me it was due to the "brick" in the cat not being quite thick enough, defect in the cat. The cat wouldn't be "bad" per se, or hurt performance, but according to what he was saying, there isn't enough material in there to "clean" the exhaust quite enough to not trip the CEL. I'd at least contact Magnaflow and see what they say about it. I think they have a warranty. Like Autozone. Ha! Kidding. That's another thread entirely.

 

High flow cats often produce a CEL. Back your post cat sensor out by using a non-fouler and put a little bit of steel wool in the space the non-fouler takes up. CEL will go bye-bye...

 

Other option - put a scanner on that will actually provide readings from O2 sensor and see if the downstream sensor reading is too close to upstream. Had similar issue on my Yota recently - had to install new cat after only 275,000 miles. Hard to find anything that lasts any more!