It all hapened at once

OWSI

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Just got done addressing 3 issues on my 2007 Tahoe. 5.3L Vin "0" mileage 183k. Driving in town (thankfully), and the check engine light illuminates along with "service stabilitrak", "traction control off", and reduced enine power. Got it home and pulled the codes with my Actron scanner. Admittedly no real sophisticated piece of equipment but it will show me live data pids as well. Got a P2135 throttle pedal position sens/sw A/B voltage correlation and P0523engine oil pressure sensor /switch high volts codes. The throttle pedal position sensor has gone out once before when the truck had about 86k on it. Never had any oil pressure issues before but the oil pressure gauge now read "0". No engine knock so I figured the sensor died or shorted internally. Should have pegged the gauge but didn't. Anyway, I went to the dealer and bought a new oil pressure sensor along with a new accelerator pedal position sensor which includes the entire throttle pedal all in one unit.
The fix: Replaced the accelerator pedal/sensor assembly - 2 bolts, 1 connector. Replaced the oil pressure sensor behind the intake manifold. If GM could have made that job any more difficult for someone with large hands I don't know how. No, I did NOT remove the intake manifold to do it. No, I didn't replace the screen underneath it as I couldn't even see the hole for the sensor let alone try to pick the screen out of there. Never had any pressure issues before and hopefully won't now. Buttoned it all back up and cleared the codes.
Next issue: Started the engine and verified the oil pressure reading correctly again and throttle response normal. No immediate codes. Took it for a drive around town. Check engine light came back on along with the stabilitrak service and traction control off warnings but no reduced power at least. Ugh! Went home and pulled the codes again. Now I got a P0171 and P0174 bank 1 and 2 lean. Sort of a rough idle as well. Looking at the live data, the mass airflow sensor was only reading 4.6 grams/sec at idle. Way low for this engine and I assume the fuel trims were out to lunch on the high side. Didn't check them as I was a little fried already. Called a local shop and scheduled a diagnostic appointment. Took it in and they found a bad elbow connector for the PCV at the drivers side valve cover causing a vacuum leak. Replaced it and all good including the fuel trims. I did pull that elbow off and it was very loose at removal and reinstallation when I did the oil pressure sensor. I kind of figured that would be the issue or at least part of it when I got the lean codes but I was over it at that moment. The truck had been having a bit of a rough idle sometimes anyway so I believe that part was on its way out. I had the shop do a smoke test on the intake just to make sure that was the only problem. But three issues all together and at the same time?!?!???
The good: The dealer was nice enough to cut me a break on the parts and the local shop did the diagnostic and elbow replacent for $85.00 so all told I'm in it for about $250.00
The bad: Well almost anyway. I could have been at 70 mph on the interstate dicing it up with 6 semi trucks when the throttle pedal decided to give up the ghost again. 2nd time now, remember? Would have been a bad time for reduced engine power and a 30 mph top speed. GM should really re-think limp mode.
Anyway, the truck is back home and seems to run fine again. If I had simply taken it to the dealer or the local shop and been hit for 3 issues, I believe I'd have been questioning if I was being ripped off. But no, all 3 things verified legit and taken care of even if I did 2 of them myself. I still can hardly believe it all went bad at the same time. Disturbing the PCV elbow likely didn't help during the oil sensor job but again, I think the part was getting bad to start with.
Anyone else have an accelerator pedal position sensor die twice? In my experience this is a 90k mile part on average. I know the oil pressure sensor has been an issue for many and as mine was 14 years old with 183k on it, I suppose its no shame for it. Still an unholy bear to replace. I'll be interested to read your thoughts on it all. Stay safe out there.
 
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OWSI

OWSI

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Valve cover has already been replaced with the "new" part. Strange thing is it's just about a dead ringer for the one that was on the truck originally. I thought the new one would differ by a lot. Got the part from a dealer so Idk. Thought about a catch can, but haven't investigated which one would be best. Open to suggetion though. Thx
 

Geotrash

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Valve cover has already been replaced with the "new" part. Strange thing is it's just about a dead ringer for the one that was on the truck originally. I thought the new one would differ by a lot. Got the part from a dealer so Idk. Thought about a catch can, but haven't investigated which one would be best. Open to suggetion though. Thx
It's possible yours was already replaced with the later version. Mine was in my 2007 by a previous owner. I'm a little skeptical that the elbow would be causing your problem. I've had mine off so many times on my 2012 that it's loose too, and no issues. Another possible culprit that can generate that code sporadically is a failing fuel pressure regulator, which is on the fuel pump in the tank. Is it still the original? Note that those codes will also trigger the stabilitrak warning as a precaution.

Yours is also the first time I've heard of an accelerator pedal failure on one of these. Others here likely have, but I haven't. When a bunch of things like that happen on one of these at the same time, my first suspicion is a bad/intermittent ground. If it starts giving you more trouble, I would remove and clean all of the grounds. It's an easy job, just takes time. Solves 90% of the gremlins on these things.
 
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Foggy

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Also, just a thought... I had the accelerator issue as well, but mine pointed to the actual
TPS on the throttle body.. I replaced both and all has been fine... I can't use my aftermarket
TB or it will throw a code.. But sometimes it's a communication failure between the pedal
sensor and the TB/TPS
 

donjetman

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That elbow was split/cracked on mine at 130k miles when I changed the vc and installed a catch can.
 

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