Not experiencing any performance loss, but these codes keep popping up. I replaced MAF sensor and looked for obvious vacuum leaks (visual check of hoses, not pressure test). Air filter was changed less than 10k miles ago. The fact that both codes pop up indicates it is probably not intake manifold gasket leaks, 02 sensors, or fuel injectors as it is unlikely both sides would fail at the same time.

I am going to try using some injector cleaner first...just in case. Could be possible fuel pump or fuel filter issue, but not sure how often these items fail. I would guess not an easy job to replace though. I have an appointment at the dealer to diagnose on the 19th, but wanted to ask if anyone has found a fix or a better way to diagnose the true source of this problem.

I did remove the side air dams when I installed a front lip. The center air dam is still attached. Would missing side air dams cause lean condition? Does not sound possible. Car seemed to run fine for several months after that mod. The codes just started popping up recently. I clear the codes, but I am not enjoying the car since I just get anxious that codes will pop up after 20 minutes of fairly normal driving. I have a 2008 base m6 with 80k miles. Mostly stock except adding Z06 dual-mode exhaust.

Thanks in advance.

 

Why was the MAF sensor replaced ??…if both lean codes popped up after replacing your MAF sensor the first place I’d look are the 2 areas in the picture below and your PCV hose connection.…the rubber bellows is either torn or installed incorrectly when you reinstalled it…anything AFTER the MAF will cause the DTC to set…why go to a dealer ??…any shop that has a smoke machine can find it if you can’t…you can spray Brake Kleen in that area (I prefer propane)and see if you notice a change in RPM…you can even spray some water and see and hear if the water is getting sucked in…having a scan tool will help to rule out a MAF issue or fuel pump but doubtful if the car runs better under load when manifold vacuum is at its lowest and a vacuum leak has less of an effect then…was the new MAF sensor OEM or aftermarket ??…STAY away from any aftermarket parts on anything you change on the car that has “sensor” in its name…always OEM !!

 

Re-torque the intake manifold bolts to spec. It is not uncommon to find them loose. Once they have been re-torqued, drive the car for a week or so and re-torque them again. Repeat this process until the bolts hold torque.

 

Thanks for the quick response. MAF sensor was replaced after the codes started appearing. I initially cleaned the original MAF sensor when the codes first appeared with MAF cleaner but the codes reappeared after a couple of drives so I opted to replace the MAF sensor instead. I bought the sensor at Autozone but picked the one listed as OEM. I think it is AC Delco. I did remove the air filter and snorkle to check for tightness of the worm screws. I also recently removed the "PCV" hose and checked (no tears) and reinstalled. I wanted to swap out the PCV valve but found out that our cars do not actually have PCV valves. If you know otherwise, please advise. They do not carry at Advanced Auto or NAPA. TBH, I checked that hose just the other day and have not yet taken the car for a spin since I did not see any noticeable issues upon inspection. I will take it out this weekend.

As for taking to the dealership, that is only after I have tried all else. I may try my local shop tomorrow to see if they can diagnose this CEL with more robust scanning tools than my simple code reader. But I made the appointment at dealer as a back-up. I have a few weeks before that appointment. That is why I am reaching out to the forum since the posts I have reviewed so far did not seem to resolve the issues. Will keep this string posted on situation.

 

Will try this. Thanks.

 

With a faulty MAF you would normally see a P0101 or 0102..you don’t have a PCV “valve” as on other LS engines…if your code reader can look at fuel trims run the engine at 3000 RPM…if short term go negative and long terms gradually decrease you do have a vacuum leak…I would redo everything you did as far as the connections and see what happens…where are you located ??…I may know of some good diagnostic shops in your area…was any maintenance done prior to initially getting those 2 DTC’s and replacing the MAF sensor ??

 

Also, check valve cover gaskets and the valve cover bolt grommets.