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Hi everyone. I have a 2000 Suburban I just bought a couple months ago. I got a couple of check engine codes I've been working through, but I'm stuck on these last three. I have the following current codes: P0175 (System Too Rich Bank 2), P0420 (Catalyst System Efficiency Below Threshold Bank 1), and P0430 (Catalyst System Efficiency Below Threshold Bank 1). I had codes for knock sensors as well, but got them replaced, and only these three codes remain. I took temperatures at the exhaust ports on the manifolds on both sides. Bank 2 was significantly hotter than bank 1. By more than 100F-150F. I took temperatures at the inlet and outlet of both cats. Sometimes the outlet was hotter, sometimes it wasn't. I have a cheap Walmart infrared so I take all temp readings with a grain of salt however. Outlet temps were within 100F of the inlets. I also took readings of the o2 sensor voltages for upstream and downstream for both banks. The upstreams appeared fine but the downstreams were pretty inconsistent. Sometimes staying pretty flat near 0.03v, other times they'd spike. They did this regardless of being at idle, or revving the engine at 2000rpm in park. I'm slightly confused at the information I gathered today, I'm trying to determine what road to go down. I'm good at working on things, not so much diagnosing. I plan on replacing both downstream o2 sensors with new ACDelco's to start, and that should tell me if the cats are bad if the codes come back, if my thinking is correct. But I'm most confused about how one bank of cylinders could be running rich, but the other isn't? Shouldn't all fuel injectors be getting the same amount fuel, at the same pressure? Everything I've found online says if I have P0175, I should also have P0172.

I have a 2014 GMC 1500 with a 5.3L. I recently replaced my CATs because I was getting the dreaded P0430 code. SO I put new Magnaflow exhaust systems as well as brand new sensors in it. I got it all in and about a day after I got it all installed I got the same code P04030. I double checked the seals and sensors and looked at the live data and it all looks on the level...the only other thing I can think is that there is a wiring issue with it...the connector on bank 2 sensor 2 looks in order so I'm a little confused as to why I'm still getting this code other than there is a ground or an electrical issue I haven't looked at.

Hello, I recently bought a 2000 GMC Sierra 2500 extended cab SLT 2wd with the 5.3L. I was very excited about this truck initially as I got it at a great price, but I am starting to become overwhelmed with all of its problems I recently discovered. The previous owner purchased this truck at an auction, and put a lot of new parts on it mechanically and cosmetically. There are a lot of mis-matched parts on this truck and I can tell it is somewhat of a "Frankenstein." One thing I noticed is that there are 4x4 buttons on the dash, even though this is a 2wd truck (no T-case). So obviously someone put a new dash on from a 4wd donor. Also, the plastic around the ignition cylinder looks like its been monkeyed with, so someone was probably fooling around near the steering column. When I test drove the truck, the only light on was "Service Engine Soon." However, when I brought my truck to get an OBDII scan at the parts store it returned 14 codes (some duplicates) which are as follows: B0017 - Passenger frontal deployment loop open B0024 - Driver deployment loop short to ground B0036 - Discriminating sensor open or short to voltage B0051 - Deployment commanded C0265 - EBCM relay circuit P0430 - Catalyst system - Low efficiency (Bank 2) P0440 - EVAP system P0449 - Evaporative canister vent solenoid control circuit But, NO lights are ever on the dash except the SES. Shouldn't the airbag or SRS light be on as well? On startup the only lights that come are the SES, nothing else. All the gauges work, although they bounce oddly when I shut off the truck. The voltage needle also twitches very slightly when I use the turn signal. Also, when I turn on the headlamps, the only thing lit up is the cluster. The radio, climate controls, and everything else is dark. And, when I cleared the codes with the ODBII scanner, the radio went off and reset itself to 1:00?! I have literally spent hours on end searching in vain for a definitive answer to this host of problems with only little success. I am guessing that the "B" codes mean that I need a new SDM? Perhaps this truck was in a wreck? P0430 might be because of a small exhaust leak this truck has, or possibly the cat is bad. P0440 and P0449 might mean I need a new EVAP solenoid or can? Please help me, it would be greatly appreciated. This truck means a lot to my little family as it is how we are getting across the country for my new job in Tallahassee. Any insights would be very welcome. Thank you all.

I'm posting this in a few different Chevy forums in the hopes of getting our story heard and getting some kind of useful advice or even just feedback. So I apologize if you have already seen this somewhere else. So I'll TRY and keep this to somewhat of a minimum, but no promises. Thanks for reading all the way through if you do. I just need some feedback and/or advice. My husband and I went down to our local Chevy Dealership and traded in our old worn out 03' Dodge Ram on 12/20/16 for a 1 owner 2008 Chevy Silverado 1500 and paid a little over $16k. LOVE this truck. It's gorgeous, all the fancy bells and whistles, (On-Star, XM, remote start, tonneau cover, etc.), seems very well taken care of, and doesn't have super low miles but seems about average for an 08'. The previous owner had bought the truck brand new in 2008 from this Chevy Dealership and had brought his truck for ANY service to this dealership. So they had all the service records. So we felt good about that. When we bought the truck, we were obviously aware of the current recall on the Takata airbag inflaters and it hasn't been fixed yet, obviously. The truck did have a light on for the airbag and the Chevy Dealership told us it was for the SDM Airbag Module. They said they would not be fixing that because there is no current recall for the SDM module in this truck. And he's right, there isn't. I searched the VIN on GM and no recall for the SDM module. So with that being the only issue (besides the Takata inflators) we decided to buy the truck. Here is what has happened since the night of 12/20/16. When my husband was signing all the paperwork for the truck, it also included signing up for On-Star which was done right in the office. As my husband started his drive home with his new truck, he got an email from On-Star for his new account about 5 minutes or so after he left the dealership. As most of you probably know, On-Star does diagnostics on any vehicle they have in their system and will send the account holder a report of their diagnostic check. So he read his diagnostics report and it indicated that there was an issue with the trucks emissions. That was all it said. Something we were not told about by the dealership and at this point in time there was NO check engine light on the truck. Our salesman was out of the office the following day, Wed. 12/21, so we couldn't get a hold of him until Thursday. Late Wednesday night I tried to remote start the truck and it wouldn't start with the FOB (remote start will not work with the CEL active). We started the truck with the key and that's when we noticed the check engine light. Not even 48 hours after we purchased the truck. We called On-Star and they told us the code is P0430 which is Catalyst System Low Efficiency Bank 2. Which is an O2 sensor or the cat. When we called the dealership and told them what was going on, it took them at least a week to get the service manager to call us back and get the truck in to test the code. OK so took the truck down to the dealership, service manager tested the code and came back out and told us it read as the EVAP Vent Solenoid and that the valve flap was stuck open and causing a vacuum leak. Told us that we should have been smelling gas fumes. No we have not. At all. Never had a problem with ANY fuel issues at all. Of course we thought that sounded a little odd. My husband is not an idiot when it comes to vehicles and from what we've researched online, P0430 is a VERY specific code to the catalyst system. But of course we TRUSTED the dealership and their service manager. Maybe they knew something that we didn't about Chevy codes. So they said they would call us to schedule an appointment to have it fixed. About a week later (this past Thursday 1/5/17), we took it in to get fixed and we drove away with our loaner. Next day, we pick up the truck, service manager said they replaced the solenoid and the check engine light was off. He also told us that the problematic EVAP Vent Solenoid they replaced had no power to it and that when they took it off, the wires were crossed. How the hell does that happen..? Obviously wires don't just cross on their own. So it must have been replaced in the past by some dingle berry that couldn't figure out where the wires go and the dealership didn't have any service records on the truck for replacing the EVAP vent sol. OR that was just a flat out lie. We were past thinking this was odd. At this point, everything that had happened since we traded in our Dodge for this truck and they only gave us $100 for our Dodge to refusing to replace the SDM module to the back door locks working intermittently after a couple days to giving us the run around about getting it in to get fixed to shotty service records about not knowing if the SDM module had or had not been replaced even though they had records that the previous owner had brought it in at least 3 separate time because of the SDM module light..honestly, I never felt good about this deal when they only offered us $100 for our Dodge. It was a worn out work truck but it was worth way more than that. I didn't want to do it. I never felt good about it and always felt like we were being played. But it was my husbands truck, I wasn't there when he bought the Chevy so it wasn't my choice. I trust my husbands judgment 100%. FAST FORWARD TO TODAY 1/10/17. The truck had been in the shop this past Thursday and Friday. It is now Tuesday and my husband was out in the truck and called me to tell me THE CHECK ENGINE LIGHT CAME BACK ON! He called On-Star and SURE ENOUGH, it's P0430. Same. Exact. Code. Hence the title I wanna drive the damn truck through the front of the effing dealership. He has called the Dealership about 5 times already and of course, no one is available. Not our salesman or anyone in the service department. Go figure. Only thing to keep in mind is we bought this truck USED and was classified as AS-IS sale. We knew that and were fully aware. BUT we are 100% certain that the definition of AS-IS does not include them make us FALSELY believe that the truck did not have an emissions problem, or ANY problem other than the SDM module. They specifically told us the only issue the truck has is the SDM module. The way this has worked out (On-Star emailing the diagnostic report literally 5 minutes after leaving the dealership, the code was already in their system) they HAD to have reset the check engine light on the truck probably when they brought it around for my husband to test drive it. They did not disclose that to us. They led us to believe the truck was in GREAT working condition and had we known about the emissions problem, we could have better a BETTER more ACCURATE decision on buying this truck. Or we could have negotiated the price and getting it fixed before deciding if we still wanted to buy it. They disclosed everything except for this emissions problem and the back door locks. And NOW even after they said they "fixed" it, the check engine light is back on which makes me think they just fed us a bunch of BS and they just reset the CEL light again to shut us up and stall us until we can no longer return the truck, imho. Buying AS-IS means you know EXACTLY what you are getting. We were deceived. Hands down 100% I believe they were completely deceptive and knew exactly what they were doing when they sold us this truck. So I'm not really sure if I actually have a question. At this point, my husband is already getting the phone numbers for Wells Fargo, our financier, for GM Corporate offices or complaint department who ever we need to call there, for the Attorney General of PA, and whoever else we need to contact. Unfortunately, they aren't BBB accredited so that's not an option. Any ideas, Thoughts, advice, similar stories, feedback for me?? Anything would help us figure out what we are going to do. Sorry it's SO long but THANK YOU so much for anyone that actually read the whole thing and is willing to give me some kind of feedback. Much appreciated!!

We've had a bunch of things happen at once to this 2007 Yukon XL 5.3 4WD, and I suspect it's all part of the same problem. Besides the above problems, we also have rough idle, and it occasionally shifts hard out of first gear. I've searched this forum and others, and I've found similar but not the exact symptoms, so I'm hoping someone can tell me if I'm thinking right on this. I don't hear any loud knocking, so I don't think the lifters are a problem. The vehicle has around 175,000 miles. 1) Replace upstream oxygen sensor 2) Check the fuel pressure and possibly replace the fuel pump 3) Check for intake manifold leaks and possibly replace gaskets 4) Check resistor by spare tire and possibly replace 5) Check/clean mass air flow sensor 6) Next check/replace the throttle body/throttle body position sensor Thanks - baskervi