Check engine light on, code P0171 with a pending P0103 code?

Hi,

Based on the codes, my first suspect is you have an exhaust manifold leaking pre-catalytic converter on bank one.

These vehicles commonly develop a leak at the exhaust manifolds. If there is a leak, it can cause the system to think the engine is running lean. Also, since it is specific to one side of the engine, bank 1, chances are it has nothing to do with a vacuum leak. A leak would affect both sides.

I checked for the most common causes and the exhaust manifold is first followed by a leaking PCV hose elbow. See pic below.

Check both of these and let me know what you find.

Take care,

Joe

See pic below.

Thank you, Joe. I will check and get back to you.

Hi,

You are very welcome. Keep in mind, often an exhaust leak will sound like a ticking.

Let me know.

Joe

No leaks were found near the exhaust manifold. I still need to check the PCV hose elbow. I couldn’t pull up the picture you sent, but I am pretty sure I know what you are talking about. One thing that I forgot to mention is when I took it to the shop and they diagnosed that the mass airflow sensor needed to be replaced, they said that it needed to be a specific one from Motorcraft, and they gave me a parts number I was unable to locate, the exact one that they recommended, but I got another one that stated that it fit that same part number. I will send you a picture of the invoice from the shop. Do you think that that would have anything to do with the problem I’m having?

Hi,

I can't do it from here, but the part number I have is different. I looked it up using your VIN. See pics below. See if you can cross-reference the one you got.

Let me know.

Joe

See pics below.

I crossed referenced and the one I got does match my vehicle. I got it from Oreily’s auto parts. To clarify what I was asking is do you think that there are other aftermarket sensors other than that specific one from Motor craft that the mechanic recommended that will work.

He said that just about any other sensor other than that specific motor craft sensor will continue to have problems.

Bill,

I haven't had any issues in the past related to the sensor brand. It is always a good idea to use an OEM part, when possible, but others work well, too.

Let me know.

Joe

The mass airflow sensor that I bought is an OEM part. It no longer shows the pending P0103 code. P0171 is only code now. What is the best way to check for a leak at the exhaust manifold?

Hi,

The easiest way is to listen for a ticking sound from the affected side. Have a helper hit the throttle while you listen under the hood. If there is a leak, the tick should be more obvious.

If you take a look at the pic below, that is the start of the diagnostics. Once that procedure is complete, the manual takes me to multiple other possibilities to check. If you want, perform the inspections and let me know the results. I can walk you through it one test at a time if you want.

Let me know. Also, is the engine running normally?

Joe

See pic below.

I replaced the PCV valve tonight and reset the check engine light. I like your idea to troubleshoot each step to figure this out. To answer your question, the engine has been running great, and I have not noticed any ticking sounds, or sounds of a hissing hose. Hopefully this will solve the issue. I will let you know if the check engine light comes back on. I really appreciate your help with this matter!

Bill,

No problem whatsoever. I'm glad to help.

Let me know how things turn out. Hopefully, the hose will resolve the issue.

Take care,

Joe

Hey Joe, I wanted to let you know that replacing that PCV elbow that goes into the manifold seems to have resolved the issue. It was working great until yesterday the hose seemed to come off the metal piece that plugs into the manifold. I am wondering if there is an adhesive that may keep it on there or would that mess with the sensor? Any suggestions?

Bill,

I'm glad to know that this has resolved the issue. As far as the hose coming off, are you able to get a clamp on it to tighten it in place? As far as adhesives are concerned, I suspect you could use something like a thin coat of Permatex and allow it to dry. I would just suggest finding something made to resist high temperatures.

Let me know.

joe

Okay, thanks so much for your assistance. I will look for a small clamp.

Hi,

You are very welcome. If you have a chance, let me know how things work out for you.

Take care,

Joe