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CEL codes after headers

3K views 3 replies 3 participants last post by  SparkyJJO 
#1 ·
Hey Guys. I had a set of texas speed catless headers installed. I'm curious as to which of my current codes are due to the cat removal? I'm throwing P0131 P0141 P0161 P0300 and P1133 (new) Are the first 3 due to removing the cats? I'm trying to figure out the P0300 random misfire code. Can't find a vacuum leak. No luck yet. Maybe the EGR valve? The P1133 is a brand new code. Maybe my front O2 is shot...Can I just throw in one of the O2's from the rear that were removed? Any help at all is greatly appreciated.
 
#2 ·
p1133 is for the slow or no response from an individual o2 sensor. The O2 sensors can only detect the presence of oxygen in the exhaust system. They can not detect the air fuel ratio. The PCM has to switch the O2 sensor high and low to help determine the fuel calculations. So It forces the AFR lean and rich at an extremely fast rate and within a small window of lean and rich ratios. The PCM will monitor the O2 sensor switch rate compared to what the target AFR is. If the sensor does not switch fast enough it will set 1133 or 1153. In short you have an exhaust leak or the most likely cause a junk O2 sensor. If you don't have an exhaust leak, I would start with an O2 sensor. P1133 can not set with p0131 already present. It might be a two for one deal. Go get a GM sensor. O2 sensors stop working after exhaust repairs all the time. I have had 2 or 3 in the last year while replacing catalysts on multiple different models. It happens. On a side note it is possible for after market manifolds to create issues with the fuel calculations. I doubt this is the case but I wanted to let you know it is possible. If you have any more questions let us know.
 
#3 ·
Mike thanks for the response. I do have very small exhaust leaks at the band clamps on the Y pipe. They are all in the Y connections. I also am having a problem with the rear flange sealing. The two flanges do not line up flush. There is a large gap on the top allowing for a large leak. Will leaks like those throw things off? I will swap the front bank 1 O2 with one that was originally in the stock y and see it anything changes. The truck has a rough idle only for 5-10 minutes after the truck starts to warm up. When its cold the idle is high naturally and as it starts to warm up the idle will get low and rough. But as the truck reaches normal temp it smooths out and is normal. I have a 5 mile drive to the highway from work and with about 2 miles to go before the highway the idle is rough at a stop. After a 12 mile highway run home the idle is perfect. Bad bank 1 O2? Bad EGR maybe? I am still seeing the same codes as my original post. I'm hoping replacing the Front drivers 02 will solve all my issues
 
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