Troubleshooting new to me Yukon XL 4WD PO codes

[ScotDail]

Hi Folks:

I just aquired an 07 Yukon XL with 123k on the clock. We drove it 250 miles with no issues, now getting a few complications. Wanted some opinions....

PO521 - Engine Oil Sensor. Seen this a few places. Figure I need to replace the oil presssure sensor and clean the screen. Oil pressure is erratic and eventually drops to zero.

PO121 - Throttle Pedal Position. Sounds like I may need to try cleaning the throttle body? This was accompanied by a PO171 and PO174 - lean bank 1 and lean bank 2. Getting a Stabilitrak warning at idle mostly while sitting at stop lights.

Thoughts? Think I am on the right track for starters? Thanks!

 

[BA.]

hate to see empty threads.

FWIW - my oil pressure sensor does the same thing. It's erratic. I have a replacement but it's freaking hard to get to the installed unit so I haven't swapped it out yet.

 

[MrAguirrechu]

*I just realized this is a year old but thought I'd give my 2 cents.*
I had the engine oil sensor code and lean bank 1 & 2 along with the check engine light and low engine oil pressure. I replaced the sensor (not fun) and the little filter below it (used a hanger). CEL went away then came back. Now I'm also getting Stabilitrack, and my personal favorite, Service Tire Pressure System (all 4 TPMS sensors are new) at random intervals. I'm leaning toward cleaning the Throttle Body first to see if there's any improvement then changing if not.

 

[2015 Tahoe LTZ]

Hi Folks:

I just aquired an 07 Yukon XL with 123k on the clock. We drove it 250 miles with no issues, now getting a few complications. Wanted some opinions....

PO521 - Engine Oil Sensor. Seen this a few places. Figure I need to replace the oil presssure sensor and clean the screen. Oil pressure is erratic and eventually drops to zero.

PO121 - Throttle Pedal Position. Sounds like I may need to try cleaning the throttle body? This was accompanied by a PO171 and PO174 - lean bank 1 and lean bank 2. Getting a Stabilitrak warning at idle mostly while sitting at stop lights.

Thoughts? Think I am on the right track for starters? Thanks!

I had the sensor and filter replaced on my 2007 Yukon and I still kept getting the PO521 code. The PCM is looking for a certain oil pressure range and if it doesn't see it, it will set the code. I only had 2500 miles on my oil when I started seeing this and got the sensor and filter replaced. what made it go away was to change the oil. I also noticed that with the older oil the AFM did not function. Fresh oil happy motor.