Just purchased a set of problems

[Lanewvr]

Just bought a 03 Yukon Denali with 190k in great shape. Left the dealer filled the tank. Boom now its misfiring, check engine light come on, flashes some, sometimes turns off. Checked codes po 131, po 171, po 300, po 650. The po 300 has me most concerned. Can that be from a faulty o20 sensor? I alao bought a bottle of Heet and put that in adter i checked codes. Please help.

 

[iamdub]

The P0300 should be the least of your concerns out of those codes. That just means random misfire which you already know about. It flashes because it's an emissions-related event that could drastically increase the engine's emissions of NOx and damage the catalytic converters. I don't mean you should dismiss it, just focus on the others to try to determine the cause of the misfiring.

Maybe you put crap gas in it (water in the station's tank)? That would cause a lean condition.

Study this link for the P0131: https://www.yourmechanic.com/article/p0131-obd-ii-trouble-code-oxygen-sensor-fault

The P0650 is odd. I'm wondering if there's a loose plug somewhere that contains circuits for the MIL and Bank 1 O2 sensor. Make sure the connections on the PCM are secure and not damaged.

 

[Scottydoggs]

Just bought a 03 Yukon Denali with 190k in great shape. Left the dealer filled the tank. Boom now its misfiring, check engine light come on, flashes some, sometimes turns off. Checked codes po 131, po 171, po 300, po 650. The po 300 has me most concerned. Can that be from a faulty o20 sensor? I alao bought a bottle of Heet and put that in adter i checked codes. Please help.

this one is a problem, its like they are trying to hide the issues by breaking the cel light. https://www.obd-codes.com/p0650

https://www.yourmechanic.com/article/p0131-obd-ii-trouble-code-oxygen-sensor-fault this one is a dead up stream o2 sensor, replace those, both up streams if you have two of em.

the lean code is caused by the o2 being bad for sure. https://www.obd-codes.com/p0171

and so is the 300 code, random missfires. stay out of the gas pedal if you must drive it.



turn your key to run, engine off, all the dummy lights should come on, look for the check engine light to be on. if you dont see it lit. id be ragging on the dealership hard and make them fix it.

 

[RED TAHOE LS]

YOUR STATEMENT ..............Left the dealer filled the tank. Boom now its misfiring,

As iamdub mentioned, your problem was OK before you bought fuel, you just never know what's in the underground fuel tanks. Good luck.
David g..........

 

[Scottydoggs]

YOUR STATEMENT ..............Left the dealer filled the tank. Boom now its misfiring,

As iamdub mentioned, your problem was OK before you bought fuel, you just never know what's in the underground fuel tanks. Good luck.
David g..........

his codes tell the whole story if you look at them and under stand them.

the fact hes got a code for a non working cel light could very well be a cover up by someone. could have been the last owner and the dealer took it in like that, either way it falls on them.

or the bulb can burn out. but tampering is more likely the issue.

 

[Lanewvr]

Well i bought the left side o2 sensor, couldn't afford both sides.

The engine light is working, so not sure why that code popped up. Unless its periodic, that could be why it turned off at times. I'll update when i get it changed.

 

[iamdub]

his codes tell the whole story if you look at them and under stand them.

the fact hes got a code for a non working cel light could very well be a cover up by someone. could have been the last owner and the dealer took it in like that, either way it falls on them.

or the bulb can burn out. but tampering is more likely the issue.

He said the light was flashing along with a code P0300. Those two often happen together if the misfire is severe and persistent enough.

That could be an old code- maybe the dealership was playing around with it and trying to hide that the CEL was on.

 

[Lanewvr]

Well replaced o2 sensor. Disconnected battery to reset computer. Reconnected and battery was dead! Did have ignition on before while i bled the brakes. Jump started it. Still misfires, cel is still on. Haven't driven it yet. But also now, shortly after starting hvac switches to defrost! Super frustrated right now! I should have known when the brakes had air in them that they are shity dealer. But it was the nicest and best driving one we test drove. Other than mushy brakes.

 

[Scottydoggs]

try bleeding the master, pump the pedal like normal, then crack the line nut off the master, if theres air you'll hear it coming out. do both lines. if you get air out out of them, re do the calipers.


might be due for a tune up with all them miles. could be another cause for the p0300 code.

 

[Lanewvr]

I bled the brakes already. They are better. But thats a good tip. Didn't know you could do that.

I'm going to check plugs and wires tonight.

Also gauge cluster lights don't work. Temp gauge doesn't work, replaced the temp sensor, still doesn't work.

Hellofa day one with the yukon.

Update.
We drove it in the rain. Misfire is gone. Heater started acting normal. Cel went off. Hit a bump and it flickers on.went on our gravel road and it came on solid again. Have run codes tomorrow.