colbywan Posted March 22, 2009 Share Posted March 22, 2009 My CEL is on and sometimes it goes back off by itself. I've checked the codes (using the very detailed how to guide here) and they are a 33 heated oxygen sensor and a 34 knock sensor. I wanted to be sure so I reset the light then continued driving it around for about a week or so til they came back and it's telling me the same codes. The truck definitely isn't running the greatest and is getting anywhere from 14 to 15 1/2 mpg. My question is which o2 sensor it the heated one before the y pipe of after? I've searched but can't seem to get any clarity on this. Do you guys think that the bad o2 could be the cause of the knock sensor code? My plans were to replace the heated o2 then reset and check later. What do you think? Thanks for any help on this guys! -Colby Link to comment Share on other sites More sharing options...
Precise1 Posted March 22, 2009 Share Posted March 22, 2009 You should only have 1 O2 sensor, down stream of the Y, before the cat (I think). Yes, change that first and see what happens with the mileage/CEL. B Link to comment Share on other sites More sharing options...
k9sar Posted March 22, 2009 Share Posted March 22, 2009 x2. There is a single O2 sensor. The connector is on the passenger side on the wheel well. The sensor is before the cat (I think) but since there is only one, it should be easy to find. PB Blaster it to ease the removal. I went with a Bosch generic that allowed me to use the existing wiring down to the exhaust then splice in the new sensor. The one with the OEM plug was more expensive. The knock sensor flags due to the engine running poorly due to the failing oxygen sensor. Fix the O2 first, reset the codes and all should be well. Link to comment Share on other sites More sharing options...
colbywan Posted March 22, 2009 Author Share Posted March 22, 2009 SWEET! Thanks for the quick responses guys! I'll replace tomorrow and then update. -Colby Link to comment Share on other sites More sharing options...
94extreme Posted March 22, 2009 Share Posted March 22, 2009 yeah, just before the cat and facing inwards and upwards a bit. hard to miss it. check for spot welds when you're PB blasting it. mine was spot welded and a real PITA to remove. you'll need 22mm open end wrench unless you have a sensor socket. Link to comment Share on other sites More sharing options...
colbywan Posted March 22, 2009 Author Share Posted March 22, 2009 I've got my PB and the new sensor (bosch universal type). I just went out and sprayed it down so it'll be ready for tomorrow morn. I don't have a 22 mm but I've got some big cresent wrenches and good size vise grips. I'm thinking I can make it work but we'll see. I didn't see any spot welds although I wasn't looking specifically for them. I'll take pics during install and update here. Thanks again everyone for the quick reponses. I can't tell you how much of an asset this forum and the people on it are to me. -Colby Link to comment Share on other sites More sharing options...
k9sar Posted March 22, 2009 Share Posted March 22, 2009 I found that once mine was broken loose, it came out easily (unlike rusty exhaust bolts that need to be worked back and forth a bit to clean the threads as you go). and use a zip tie to control that universal connector and keep it off the exhaust (depending on where you splice in). Link to comment Share on other sites More sharing options...
colbywan Posted March 22, 2009 Author Share Posted March 22, 2009 All done. I used cable ties in a few spots to keep the wires away from the exhaust. I reset the codes so we'll see if any come back or not. Seems to run a bit better but it's really to early to tell. I'll know more after driving it around for a few days. The old one was really white here it is just barely unscrewed so you can see the tip. Thanks again guys! -Colby Link to comment Share on other sites More sharing options...
Slick Posted March 23, 2009 Share Posted March 23, 2009 my rig threw the same codes, it was the o2 gone bad, all was well after changing the o2 sensor out. good luck! Link to comment Share on other sites More sharing options...
colbywan Posted March 23, 2009 Author Share Posted March 23, 2009 my rig threw the same codes, it was the o2 gone bad, all was well after changing the o2 sensor out. good luck! Well after a couple days of driving I can tell you aboslutely this was the prob! It runs way better. But one thing weird is that I cleared the codes the CEL was gone but today while driving the light came on for like 20 seconds then went back off never to come back as of yet. The truck is running great so who knows... What does it mean? Hmm.. Now I just need to focus on getting some broken studs handled but that's another issue. -Colby Link to comment Share on other sites More sharing options...
Precise1 Posted March 24, 2009 Share Posted March 24, 2009 Damn, we were right for a change... Glad it was easy. B Link to comment Share on other sites More sharing options...
Kingman Posted March 24, 2009 Share Posted March 24, 2009 What was your rig doing? Link to comment Share on other sites More sharing options...
colbywan Posted March 25, 2009 Author Share Posted March 25, 2009 What was your rig doing? It was running crappy, it was hard to drive smoothly unless it was floored. Not very much power at all. CEL was on and flashed 2 codes. 33 heated o2 and 34 knock sensor. It's running good now but one wierd thing is the CEL came on for like 20 seconds then went back off. But the trucks running great so far. -Colby Link to comment Share on other sites More sharing options...
Kingman Posted March 25, 2009 Share Posted March 25, 2009 It was running crappy, it was hard to drive smoothly unless it was floored. Not very much power at all. CEL was on and flashed 2 codes. 33 heated o2 and 34 knock sensor. It's running good now but one wierd thing is the CEL came on for like 20 seconds then went back off. But the trucks running great so far.-Colby Ah. Glad to hear it was a straightforward no-hassles fix! Link to comment Share on other sites More sharing options...
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