Okay, I’m not a big car guy, I have a small knowledge of cars and probably a lot less than others but my 2009 Chevy Malibu had a check engine light turning on and off for the mass air flow sensor. So i replaced it. The light didn’t go away, even after driving roughly 50 miles. I decided to replace the air filter, still on. Now, I believe it is my drive belt, (belt under the air flow sensor and to the left of the engine) is making a whirring noise, and stops when I pour water on it. I don’t know if this was a coincidence that it happened after changing the filter or if i screwed up big time. The engine sounds weak, the check engine light is still on and the belt is whirring. Any advice?
And it’s currently Sunday, so taking it to the mechanic is on hold.
So Sunday, take it to an auto parts store and they will read the codes for free. Post them back here in the form of the code… P0123, that form and we’ll try and help.
he code was P0171. But i changed the sensor and filter and is still there. And the first guy says a belt won’t cause the light to go on so I’m assuming it’s the same code
Exhaust leak between engine and first oxygen sensor
Note that the MAF problem is not the ONLY reason this lean fuel condition can happen. On a V6 engine with 2 cylinder banks fed by one MAF and one filter, why would only one side run lean? Answer, it likely wouldn’t, both would run lean. So MAF isn’t the problem, but you already know that now.
Only a sticking or failed injector or bad O2 sensor on one side or an exhaust leak on Bank 1 (from the list) would cause this. And you aren’t showing a failed O2 sensor code and didn’t complain of any “ticking” noises at idle so…
Your problem may be a sticking or failed injector on bank one. THIS is why we ask for the actual code.
Ooops, thought it was a 3.5 V6… that was another post. That only opens things up, unfortunately to all of these possible problems. Makes diagnosis more involved.
How many miles on it? 10 years and 100,000+ could be a weak fuel pump - a pressure test should answer that. I don’t think this has a separate, replaceable filter.
A sticking fuel injector may be heard (or actually not heard) using a long skinny screwdriver placed on each injector and your ear on the handle. The “snap” of the injector should be evident. No “snap” and that may be your sticking or failed injector.
Run your hands over and around the air intake pipes and hoses after the MAF. Any leaks around the MAF will throw the code.
Listen for exhaust leaks, tick, tick sounds.
And if you don’t have a code reader that can reset the CEL, unhook the negative terminal for a minute or 5 to clear the codes and see if they return. Actually, I’d try that first if you haven’t already reset the codes.
It has 123k miles, and I’ve tried using my hands to find leaks but couldn’t. I also disconnected the black terminal on the battery and it didn’t reset the code by instead made the car sound weak when turning on
Then you still have the problem setting the code. If it sounds weak when you “turn it on” - crank it maybe? then you haven’t gotten the battery cable clean or tight.
I think you are waiting for Monday to get it into a pro.
I believe it will also reset all of the learned engine operation memory and set it back to the original settings until more miles and key cycles are done. That could be why the engine is sluggish now. I think its time for a shop to take a looksee.
Running weak + lean code.
I’d suspect fuel pressure issue: fuel pump or fuel filter.
A vacuum leak (from manifold gasket, hose etc.) would have biggest effect at idle.
Belt noise: just change the belt if it’s over 5 years old; and cross fingers.
