I went to pick up my 2001 Expedition that has a 4.6 V8 from getting the AC compressor, etc. replaced. That was about $1200. I trust this place for auto AC repairs over the years.

The vehicle has 111,000 miles on it. As I was backing out to leave I saw the CHECK ENGINE light was now on. It had not been when I took it over there. They checked for a code, but didn't look back under the hood.

They said it was for the Cam Sensor. They cleared it and I asked them what if when I turn it off and start again the light comes back on? Should I blame them?

The owner said jokingly "Don't ever blame us..."

He saved me a LOT of money years ago when I just had a little hose leak and someone wanted to replace the compressor etc. on another car we had.

Naturally, the light came back on and I stopped at Auto Zone since I was half-way home. It is the P0340 code.

When we looked at the monitor in the store at first both of us thought it was right next to the compressor, but it isn't. The gal showed me where it was on my vehicle outside so I could see if it felt loose. It looked OK (the connector) and I un-did it and re-attached it. The light stayed on.

Looking this up online it doesn't sound like a cheap fix and we have had some many auto repairs between three vehicles these past few months! I just had the fuel pump replaced last month ($400). Does this just sound like an unfortunate coincidence or what?

It doesn't look THAT physically close to where the compressor is (on the left). AAAAAGGGGGHHHH!!!!! I am not a mechanical whiz, but can do some stuff on my own. This does not sound like one of them.

 

I cleaned the connector better and made sure it was firmly in place. The SERVICE ENGINE SOON light remains on. I don't know if you need to disconnect the battery to make that go away at least for once. I tried that when trying to clean my Mass Airflow Sensor.

The vehicle has not been running funny or rough, but like I said, the light was on only when I went to pick the car up.

At least I got the new hood lift supports on my daughter's car OK today. So much for my saving $20 if I have to take MY vehicle right back in. Here our 30th anniversary is this month and it looks like we are spending our money on repairs instead.

 

Last night I cleaned that connector more thoroughly and made sure it was firmly back in place. This morning I disconnected the battery to clear the code. After starting up the second time the trouble light came back on.

Back in November it had codes of P0171 & P0174 and it was checked by our mechanic. He said the PVC vacuum line was degraded and leaking and replaced it. No Service Engine Soon light since then till yesterday.

 

I have a code p0340 (cam sensor) but am not have any bad symptoms my truck runs fine like regular no loss of power and it does not idle rough what could it be causing the p0304 to cut on and where is the the cam sensor at on my check am not a mechanic but i just want to visual check it to see if a wire became disconnected also about a week b4 the light came on. I had to put on a used 2000 lincoln Navigator with the 5.4 alternator on my truck and my truck is a 1998 ford expedition with the 4.6 engine would this have anything to do with the p0340 code on my truck. The alternator works fine when my neighbor brought it was brand new but he stop driving it and let it sit soon after buying it for a couple years when i need the alternator he sold me his so do you have any ideals or ways i could fix this code on my truck

 

I bought a new sensor since I can get at it without having to remove a bunch of stuff (though it is a tight fit). I cleaned the old one and re-tried it after the guys at AutoZone said to try that. The wiring harness doesn't look like it was hit or is damaged.

The trouble light still came back on, so I put the new sensor in ("once you install it, you can't bring it back"). Well, I wasn't getting my hopes up too much since the old sensor looks OK...and the new one didn't solve the problem. The trouble light came back on after I started the second time.

Guess it is mechanic time since I did notice it seemed to 'miss' or hesitate some today. It was not doing that before the AC repair/trouble light. AAAAGGHHH!! I figured it was worth trying since I could get at it.

 

I would change the crank shaft sensor first, its mounted above the ac compressor, at the bottom of the timing cover v area and the harness is draped over the compressor, the ac compressor has to be dropped to access it, but not disconnected, an issue with this sensor can give you a p0340, try to use oem or delph

 

If it is the crankshaft one then I would think maybe they did something installing the new AC compressor etc. I called our one mechanic today and talked to his wife. She thought maybe the new compressor is 'pulling' more now and it is throwing something out of whack. Maybe it really isn't the AC repair folks' fault.

Just a while ago I recalled on my earlier research that folks mention them being on both 'banks.' Shouldn't there be another one? AutoZone doesn't show a diagram that is for my year, but what they do show was where the one I replaced was (LH CMP Sensor). I hope the RH CMP isn't hidden by something.

When I look at that diagram for the OTHER one it doesn't look the same...it was easy to spot to one I replaced.

I just took a shower and now I want to see where that other durn sensor is!!!

Obviously I am not Mr. Auto Mechanic, but the AZ gal only pointed out the one and one the video I watched he was replacing the one I replaced. Doh!

 

I believe there is only the cam and the crank sensors on your engine the cam is on the drivers side timing cover by the upper timing gear, the crank sensor is even with the crank on passenger side of crank pully, it points down and the connector is between the ac compressor and the block and they are different looking, this sensor reads the the timing sprocket located in front of the chains, hope this helps

 

I've got to remember that the diagram in question was NOT for my year or same size engine. Maybe it has only one cam sensor. No one at either Auto Zone said there was more than one to check/replace.

This is what comes up every time on their site--not the exact same engine or year:



Where #7 is is where I replaced mine.

 

The one the gal from AutoZone pointed out to me is on the driver's side. I have driven yesterday and today and is does not seem to be 'missing'/hesitating at times like it was when I drove to get the cam sensor.

It does sound like the new compressor makes more of a noise (as I could hear it at times when accelerating even with the radio on). That was yesterday afternoon in 100 degree heat. Almost like somebody blowing a toy train whistle faintly. Was not very noticeable this morning.

I sure don't see another cam sensor unless somebody can point me to a photo or diagram of where it is on my vehicle. I called Precision Tune and he can't get to us till Friday. He also thought that there might be two cam sensors. Every search I do does not turn up my vehicle/year. Or it's the same AutoZone diagram we saw in the first place.

Mine does not look like the diagram on the passenger side. Should the new sensor have made the light go off if that was the problem? I have read that would be the case. Or do I need to get the codes cleared with a sensor (like at AZ) to be sure?

 

Your engine only has one cam sensor, did you disconnect the battery and wait a little bit and reconnect it , this clears codes

 

Thank you for that update! I did that both when I tried to 'old' cam sensor after cleaning it (AutoZone advised me to give it a shot) and after installing the new one. It sat there for a decent amount of time, not just a few minutes.

And both times the FIRST time I'd turn the ignition the trouble light was off. I had some other sensor problem (maybe that was the MAF) and it stayed off for a few days after I cleaned it twice and then came back. I think that was what ended up being a vacuum line leak (I'm looking at my receipts in the folder).

I did not go and get the thing cleared. It definitely did not come back right with the 2nd start. After the AC repair place cleared this code with a scanner it came back with the second startup.

I'm going to see how it runs, but I know my wife will say "I don't trust it until you get it fixed" if she ends up having to drive it...especially out of town.

 

At Precision Tune they say there is no voltage through the wiring to it, as he also tested the old cam sensor. So, it 'may get pricey' if he has to trace the wiring all the way back. I asked if he thought this had something to do with the AC repair and he said probably so. He is waiting to print out some diagrams.

I phoned the AC repair place and the owner is going over to PT to see what's what. We both know the crankshaft sensor is where you have to remove the compressor to get to it. So, it seems like that might have something to do with it.

UPDATE-The AC guy just called and he said he talked to them and told them to 'fix it,' as they are not experts on that kind of stuff. I've always trusted the AC repair place and that's why I wanted to go to someone he knew. It just didn't seem very likely that it could be a coincidence.

Now my wife doesn't really want to go back to them for AC repairs anymore, but it's not the first time I have picked a car up and something else was wrong or the original problem wasn't fixed. It sure wasn't our fault and it doesn't make me happy that they didn't even look under the hood when I showed them the trouble light.

 

Im surprised that your A/C place didnt want to put it back on the lift to double check their work, and check the crank sensor wiring, plug, and connection after you gave them 1200 dollars for a noisy compressor, and let you leave with a check engine light on that wasnt there before and is related to the crank sensor that is right at the repair point, hope he pays PT for your repair, my thoughts

 

The Precision Tune owner just called and he is giving up. He tried a Ford cam sensor and it did the same thing (light stays on). He can't find a diagram to trace the wire all the way from the cam sensor.

So, it's either go to Ford, someone else or just keep driving it. He is not charging me anything. I asked about the crankshaft sensor and he said he took that out and put it back. He said the car would not even start if that was bad.

There's another local tune-up place I trust (where I started going after my father and I got mad at Precision Tune years ago). Back then I got charged like $300 or something for a part and it didn't fix the problem...he was then going to try something else.

This other place said he would be able to return a part if it did not fix the problem as long as the part was not messed up. I was upset and my father got VERY upset and I figured I'd probably never go back to Precision Tune. But, the other mechanics NOW that we trust always recommend him when it is something beyond what they can do. The 'incident' may have been 20-25 years ago.