Mechanic is stumped

We bought a 2011 malibu used from a private party. It ran great, no dash lights, no weird noises or hesitation, everything was good. Then a couple weeks later it started up, drove 100 yards and stalled. We couldnt get it restarted so we had it towed and our mechanic found a problem with the battery connection, so he replaced the connector. Fired right up and all was good. Then 3 days later while leaving for work in the morning it stalled out before making it to the end of the street. He covered the tow this time and wound up replacing mass airflow. Again all was well and the car drove great…for 2 weeks. Then one day, pulling out of parking lot at work it stalled out again and would not start. It has been at the shop for almost a month now and the mechanic is stumped. There are no codes. He checked all the fuses, camshaft solenoid and sensors, made sure the maf he replaced wasnt a bad part, wiring harness, idle air control, fuel pump, fuel pressure all good. It starts and then immediately dies. It’s also crazy that it was repaired and it worked but then the issue returned… twice.
Any ideas? I dont know if he’s just frustrated and needs some fresh ideas or what, but I gotta figure out the fate of this vehicle soon.

If he didn’t check the Crankshaft Position Sensor, he may have missed the source of the problem.


Did he check for a signal from the crankshaft position sensor?


I would just add that the fuel pressure was good when he checked it. However, that does not mean the pump is working fine all of the time. They can intermittently quit and then start working again at some point. My daughter’s Mitsubishi was doing this some years ago. I kept that car for 5 days and it ran fine…until it quit on the road on a 100 degree day. It was the pump, but thankfully it fired up 10 sweat soaked minutes later and got me home. New pump solved that one.

The crank sensor would have been a better option than the cam or MAF sensors.

What I might try is to run a jumper wire on the fuel pump relay terminals. Bone simple to do. If the car starts and runs fine then the ignition switch is a suspect although the PCM could possibly be at fault. Hope that helps.

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It may have been crank and not cam. I asked him about both of these possibilities, either way, and he said there would be a code. He said if the solenoid was bad there wouldnt always be, but he switched them out and it didnt resolve the issue.

Read the article again.

It states:The check engine light doesn’t always come on


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Also the fuel pump is fairly new…less than 5000 miles on it.

Theres no light. Also no code
Article says…copy/paste
scan tool will show a code between P0335 and P0338. The check engine light doesn’t always come on, though, so you could be experiencing any of the above symptoms for some time before you see the warning light.

This reads to me that there would be a code but not necessarily a light. So…theres neither a code nor a light.

Mechanic said theres no way the crank position sensor wouldnt throw a code. So is he wrong about that?


Good luck!


You need a much better mechanic

Absence of codes means NOTHING

It also sounds like the guy’s not very systematic in his approach

I’ve fixed tons of driveabity problems, no starts, stalls, etc. which never threw any any codes

I’m sure most of the professional mechanics on this website could say the same thing

Completely wrong

About 1/2 of the faulty crankshaft position sensors I’ve replaced never generated any code(s)


Concur. The first step is to determine if the “engine won’t run” problem is fuel or spark. It’s unlikely to be both, almost certainly it is one or the other. Has that been discovered yet? If not, suggest to ask your mechanic to focus on that.

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Yes…fuel, fire, air…has been investigated.
He has been our mechanic for 10 yrs and we have never had a problem like this with him.

So I guess I’m trying to determine if our long standing relationship is affecting this. Maybe he feels a lack of urgency because he knows we are loyal.

He HAS seemed systemic in his approach. First he said he checked for spark issues, and that’s why he replaced the battery cable and connector. It fixed the problem, but only for a few days.
So next he checked the air. And that’s why he replaced the mass airflow. And it fixed the problem. But again, only for a few days.

He told me when I asked about the cam and crank sensors, and he said it would be a very expensive guess, and he cant believe there would not be some kind of code. He doesnt wanna fix that and have it break down a few days later.

Do you guys find it odd that the other things he replaced fixed the issue but only for a few days?

I have also searched these forums for similar start/stall wont stay running type issues in a malibu and I find lots of posts about similar issues and none of them have solutions or seem to have resolved the issue.

Could this be an issue with the computer? Could it be in need of an update? Or just be bad?

I am gonna talk to him about ths crank sensor. I know it could be an expensive guess, but I dont want to scrap this car over a couple hundred bucks…
I’m by no means a mechanic but i do know how to google and I have a basic understanding of how cars work and what parts do what things. And my average joe research points to the crank shaft sensor too.

The people we bought the car from had this issue too, and didnt disclose it. I found out when I went to the OTHER mechanic across town and got all the service records. Apparently they replaced the fuel pump and it fixed the issue. But only for a short time. The service records say “car stalls and will not restart. Has happened several times” they did a diagnostic which was inconclusive. So they sold the car.

He said it wasnt “testable” and that the “test” is the code.
So…I’m gonna get on him about this. I will go to the shop and make him test it in front of me on the spot.
If I am the one who has to do a portion of the “labor” he will be giving me a reduction in labor cost.

In his defense, for what its worth, he only charged me for parts after he didnt fix the problem the first time. So if I have to figure out the problem myself hes gonna have to come off some of his labor costs. I know it’s been a lot of his time, and he should be paid for his time. But my time is worth something too and he has had my car at his shop for more time than I have had this car in my driveway.

If he cant figure it out i guess we will take it to a chevy dealership and go down that rabbit hole, or trade it in.

Lousy time to trade but that seems like the best way to end your problems if 2 shops can’t solve this.

As the car sits right now will it not start and run? If so, then my suggestion would be to jump the fuel pump relay terminals which I mentioned earlier.

As mentioned, crank sensors do not always set a code and generally speaking they are not that expensive. I’ve never changed one on a 2011 Malibu but the one on my GMC Sonoma can be changed in less than 3 minutes. Many crank sensors run in the 15 to 50 dollar range so it is not an expensive guess and much more feasible than what has been done.

The parts he was throwing at your car was fixing nothing for a few days. It’s all coincidence due to an intermittent problem;

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Depending on the type of crank sensor, it can be tested with a scope/meter or scanner.



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I’ve done a crank sensor on a 2010 Malibu. Easy access and very in expensive. So much so that I would even shot gun it at this point.

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Thanks everyone.

Gonna just go with it. I’ll update later

I’m not saying it’s not a crank and what the hey, that’s cheap, but I always think fuel pump when I’ve had these symptoms. I’ve had pumps fail very early. So was the harness replaced with the pump so a good connection was insured? Did they replace the relay at the same time to make sure the contacts were good? Intermittent are hard to find and I’ve had my car towed for a bad pump and started right up again after the tow. I’ve had two crank sensors go. The one shut me down completely and the other provided a chuggle under load until it failed completely. If your guy can’t do anything if no codes were found, might want to try a different guy.