Getting CEL codes P1051, P1168, P1278 and P1279.

Replaced O2 sensors back in November, but still getting rough idle, poor fuel economy and many codes. I believe it was branded "Ultra Power" from RockAuto.

Shop it's currently at recommended a valve cover gasket (recommended by many other shops, known issue) and factory O2 sensors because, "Infiniti is sensitive."

Factory sensors are very expensive.
Getting quotes of ~$500 for valve cover; $750 for O2 sensors.

Open to some other ideas, too!

 

Shop is right about the sensors. It's well known on this forum that OEM is the way to go for few to no issues with new sensors. Some people have purchased aftermarket and had no problems but there are far fewer happy members than unhappy members that did. So we recommend OEM but look around for better pricing. I needed a new cam position sensor bank 1: Nissan wanted $143, Infiniti wants $182 and I found new OEM's on Amazon for $78. Exact same part but a vast discrepancy in pricing.

 

Okay!

I saw around that OE could be Bosch or Desno; is it better to just go straight to Infiniti?
Any DIY guides on removal/replacement of them?
They look TOUGH to get to/get torque on them.

 

Just look for genuine Nissan OEM parts wherever you can get them the cheapest. There is a lot of information here and on the internet on how-to replacement procedures.

 

We just picked up the G35 back from the shop who did a full tune-up and valve cover gasket.
They said we could replace some vacuum lines and they marked them for us- but then they ended up needing an extra day and did the lines for us as a courtesy.

We put the G35 up on ramps today and aren't able to get enough leverage on a breaker bar/ratchet to break the O2 sensors loose- up top same thing.

I only have a normal Ridgid Impact Driver, and not a full Impact Wrench.

Any thoughts/ideas?

 

They make special O2 sensor wrenches but no matter what you do make sure you spray the sensors/bungs liberally with a penetrating lubricant like Liquid Wrench or PB Blaster a couple of days before then again the day before you plan on working on the car. Hopefully that will work it's way in and release some of the pressure so they'll come off. If they're rusted/fused I'd recommend going to a local muffler/exhaust shop. I had to go this route on my GF's old truck, took the mechanic 10 minutes to cut a new hole with a plasma cutter and weld a new bung to the pipe. Cost us a whopping $35......

 

Infinitipartsdeal.com has been my go to oem parts store for parts that I know fit the car--I don't believe they are an Infiniti dealership, so, they can't verify part fitment on the spot, but they are always cheaper then the dedicated dealship sites, like Infinitipartsonline which is a more knowledgeable dealership site. When in doubt, I'm terrible and I call Infinitipartsonline for fitment and then order from Infinitipartsdeal. Hey, money is money!

Sensors on Infiniti parts deal are $167 - $173 each.

 

Also try Amazon. I needed a camshaft position sensor bank 1 so called the dealerships then looked online:

Infiniti $183
Nissan $164
Amazon $78

All OEM and the exact same part, go figure..............

 

Yep, one camshaft sensor was 88 and the other 98 on InfinitiPartsDeal, so, in the ballpark.

 

@rawfuls, how bad is your gas mileage? I have no codes, but mine is horrible. About 120-ish miles on a full tank of 91 Shell...