There is a screen/filter in the back of the engine under the oil pressure sensor. If that checks good there can be at least two major issues.


The oil manifold that runs the cylinder de-activation and or hydraulic lifters can be damaged.


There can be camshaft bearing issues in the block.


There may be a pick up screen clogged


Or all the above.


Do NOT do a bunch of part replacements if any major damage is found.


Get a NEW factory engine.

 

When I bought my 09 with 120k miles a few years back it would have the low oil pressure light come on after driving 10-15 minutes. After the dealer replaced the oil pressure sending unit and screen to no avail, they decided it was a communication error from the dash computer to the ecm. They reprogrammed and that took care of it. I have put 40k more miles on without a re-occurrence.

 

I purchased a new 2010 GMC Yukon Hybrid 2WD and have had it since. It's now August 17, 2017 and finally got my first "engine service" light at 117,000 miles. It read the following:

P0AC4 - Hybrid Powertrain Control Module Requested MIL Illumination
P0AB9 - Hybrid System Performance
P0AC4 - Hybrid Powertrain Control Module Requested MIL Illumination
P0AB9 - Hybrid System Performance
P0AB9 - Hybrid System Performance

Did a little research which stated that it may may need a Hybrid Battery Replacement.

On another posting, someone just ended up resetting the codes which worked fine thereafter.

I just reseted the codes to find out if they'll return. Hope I get some luck.

I want to ask anyone out there if they've done the same or have gotten the same error codes?

 

P0AB9 may be that axillary pump or a bunch of other things. Most likely not HV battery

 

Makes since. Once in a while i'll get that electrical humming noise. Found something on YouTube which i can relate to.


Do you think it may need replacement?

 

All it does is makes noise. Harmless otherwise.


A transmission replacement is about the only fix.

 

Speaking of noise, my wife is complaining about some interference type sounds coming out of the speaker above the driver's window. Any idea what could be causing that?

 

That's an aspirator (small fan) for the climate control system, without it the auto HVAC will not work properly sometimes they go bad from dust and whatnot and buzz, I believe they are like $25 online($30 at the dealer), I do not know what is involved in replacing one because I've never actually seen one go bad in person.

 

That sounds like something in the cooling fan.


For my part, 143,000miles so far. I've replaced the front left wheel bearing. (Probably wasn't bad but it was cheap and I already had removed it from the car)

2 of the AFM lifters (1 and 7)collapsed while on a 2K mile round trip. Drove it about 1600 miles like that (because I had no other choice). Dealer replaced the bad lifters under warranty for about $2200.00 ran great for about a year and a half. Last week on the way to work my number 6 cylinder stopped firing on me. I drove it home and took the wrangler to work. Got home home and checked spark. (good) plug looked clean. Tested compression and got 0PSI on cyl. 6. Checked compression on #1 to make sure new gauge was good and got 125psi.
Just ordered <HYPERLINK
I had to call them to get new lifter trays on the order. for some reason they don't include them in the kit.
Also ordered a Per their recommendation.
Hit a bad rainstorm on one of my 2K mile journeys and blew the fuse for the security system. stuck me for a couple of hours on the side of the road till I figured that one out.
Dealer replaced my 12V battery and fixed a rear door lock before I bought it.
Only problems I've had have all been engine related. Nothing with hybrid Electrical system.
I do get a jolt/surge while braking when the transmission drops from ICE to Motor every so often but its not repeatable enough to diagnose. Sometimes its every time I stop and most times not at all.
I much prefer driving it over the TJ but its nowhere near as dependable The AFM system seems to be the biggest weak point. I plan to drive it till it eventually dissolves. If I have another lifter issue I'll switch to non-AFM lifter setup. I like the cylinder cancellation feature. Just wish it was more robust.

I also replaced oil pressure sensing unit and filter screen. It dropped to 0psi one morning. But sensors go bad so I can't blame GM for that.

 

Just turned over to 140,401 this last fill up. Averaging 20.1 mpg on the computer but getting between 21.0 and 23.5 by actual checking, depending on the mix of city and hwy driving my wife does. No problems in the last 10K except for the Nav/radio/back up camera screen,,,which seems to be failing. It works like new for a week and then craps out half the time the next week. Everything still works, apparently, except there is nothing on the screen. My wife really depends on the back up camera so I will take it to the dealership next week while she is out of school to see what they can do about it. Don't want to spend a lot on it but don't want her to back into anything either. We shall see.