P0340 Code

[cotton66]

got an used 2001 EB expy with 131,000 miles got a code of P0340 but now cleared. autozone said cam sensor around $17.00 The service engine light is now off. anythoughts on this being sensor error or sign of something needing attention?

 

[wuzit10538]

P0340 code after AC repair yesterday

I went to pick up my 2001 Expedition yesterday 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 ****, 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. Last evening I cleaned it more thoroughly and made sure it was in there good. I disconnected the battery to clear the code this morning, but the trouble light came back on the second time I started.

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.

 

[FordandPolaris]

Well first of all if the truck does not run any worse, you can drive it and be fine. My CEL was on for so long it burned out.

Next, I have never looked into doing a Cam position sensor on these trucks, but on most cars, they just pull out of the head and are replaced with another unit fairly easily. Can you reach the sensor itself or is the connecter a long way from the sensor? I do not even know where that would be on these trucks, so a picture might help.

EDIT: Figured I would just look into it. This is a thread containing the position of the CRANKSHAFT position sensor, which is very close to the A/C compressor.

http://www.ford-trucks.com/forums/975407-2003-expedition-p0320-trouble-code.html#post9128178

 

[wuzit10538]

On my 2001 Expedition the AC compressor is more on the left side of the engine and the cam sensor is to the right of the front. The AutoZone diagram at first glance made both of us THINK it was right near the compressor.

The positioning looks a LOT like this YouTube instructional video. This video makes me think I can do it. The first one I saw had more complicated steps. He's working on an F150. Looks so much like mine under the hood.

How To Replace A Camshaft Position Sensor (CMP) - YouTube

I just went and looked again and MAYBE I can squeeze in and not have to remove all of that stuff to do it. If I was scrawnier it would be easier. Thank you for responding!!

I may still call our main mechanic and ask for a quote or advice (my wife never likes me to try things on my own), but I can accomplish some DIY tasks. It sure helps to have YouTube videos. Got my lawnmower running again because of that.

 

[FordandPolaris]

I have changed upper and lower ball joints, wheel hubs, and rear control arms all thanks to You Tube. I would say if you can reach it, do it. It will save you a lot of money.

 

[wuzit10538]

I bought a new sensor today and can reach the old one without taking off a lot of the air filter, etc. stuff. At AutoZone they said sometimes if you take the old one out and clean it it might still work. I tried that, but no such luck.

The wiring harness does not LOOK damaged or like it got hit , so I guess I'll try the new sensor. "Once you install it, it's yours." With my limited expertise I'm not sure how I'd tell if it was just the harness. Well, if the new sensor doesn't fix it that may be a sign.

When I drove it today it did seem to 'miss' a bit at times, so I don't think it is just a false alert.

 

[wuzit10538]

AAAAGGGHHH!! The SERVICE ENGINE SOON light came back on the second time I started. The sensor that was in there looked OK, as does the harness. Rats! The new sensor didn't do the trick!

Guess I'll have to call my mechanic (well, we trust two of them for general repairs).

 

[stamp11127]

FYI:
OBD-II Trouble Code: P0340 Camshaft Position Sensor Circuit Malfunction

Sensors are touchy. We will have a bus come in with one failed abs sensor and it will leave with 4 new ones once we're done. Put a replacement in and another one fails. Once that happens we replace all of them.

 

[wuzit10538]

Now I recall 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.

Apparently the Crankshaft one you have to lower the AC compressor, but the code I get is not specifically for that sensor. 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. I'll keep hunting online for a better reference. The garage is still pretty warm (I'm in south Texas).

 

[FordandPolaris]

Go to a Ford Dealership. They have good parts diagrams in the parts house. Then once you see what you need to see, tell them thanks for their time and go back to autozone for your other sensor.

 

[stamp11127]

Rock Auto list a crank sensor for yours. Usually they are located behind the harmonic balancer and secured to the front of the block. If you can get a graphing scanner that will read each sensor you can see which one is acting up.
The wiring diagram for my 99 only shows on Cam Pos. Sensor on the driver side with one crank sensor on the pass. side by the a/c.

 

[wuzit10538]

Rock Auto list a crank sensor for yours. Usually they are located behind the harmonic balancer and secured to the front of the block. If you can get a graphing scanner that will read each sensor you can see which one is acting up.
The wiring diagram for my 99 only shows on Cam Pos. Sensor on the driver side with one crank sensor on the pass. side by the a/c.

Thanks, that's what someone on another forum also said.

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.

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? Precision Tune can not get us in till Friday.

 

[wuzit10538]

Yesterday I went back to AutoZone just to be sure if it was still the same code (yes) and to see if the code had to be cleared by the scanner (she said if the new part fixed it it should go off--it didn't). She said it may be in the wiring.

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 P.T. 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.

If we don't have to pay for the P.T. repair and I'm just out the $18 for the sensor I installed myself (that it didn't need), then I'll be glad to leave this crisis behind.

 

[wuzit10538]

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. He said the sensor I took out tests OK. Either there is no juice in the wiring to it or not enough.

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.

I talked to the guy at the local tune-up place a few minutes ago and he said he'd charge us like anybody else...$90 an hour and we'd probably be looking at 2-3 hours.

If it is something IN the computer then we would end up going to Ford for that in the end. He agreed that if the crankshaft sensor was faulty the vehicle would not start.

I wanted to see what he thought before I called the AC repair guy again. Obviously he isn't going to try and diagnose it out of the kindness of his heart. It does seem a bit odd to me that the car was missing and hesitating after the trouble light first showed up.

With the new cam sensor it stopped doing that, but the code and light remains. I feel like we are in an awkward spot now. If we just keep driving we never know if there is a new trouble code unless we have Auto Zone check. I don't know if the AC place will be eager to have FORD work on it!

 

[wuzit10538]

The car still does idle low sometimes now and didn't before the light stayed on. It's almost like it gets that low idle 1 out of every 3 times you start the car. My wife says it makes her worry to drive the car now, but if Ford tells me it needs a new computer or something that will suck.

A local tune-up guy via Facebook told me it could be the coil packs are going out. He has kind of a specialized place to soup up folks' rides it sounds like. A worker at the Wal-Mart (who was moving over to Discount Tire the next week) auto section recommended him. The guy who runs the place said they don't normally do maintenance on things like that, but I can ask for more details or have him look at it.

 

[bedrck46]

The wiring diagram for the 2001 shows only ONE sensor

 

[bedrck46]

prints attached

 

[stamp11127]

Since the wiring diagrams only show two wires going to the cam sensor we can assume that it is a Hall Effect type sensor. Those produce a voltage pulse as the engine is running. The pcm uses that pulse to determine the respective location of the cam.
When you were at PT, did they show you the lack of input from that sensor? The higher end scanners can be set to monitor specific sensors or watch for specific events. That is standard practice in our shop as we diagnose problems.
If there isn't any input from the sensor after being replaced you would check the wiring harness next. You can do that with a voltmeter and some time.
Let us know if you want to tackle it, sounds harder that it really is - as long as you follow the instructions.

 

[wuzit10538]

I talked on the phone to the Facebook guy and he had suggested that (coil packs) without knowing for sure if it only had one sensor. When I said I knew it only had one then that changed things. He said it might be the PCM then if there are no wiring problems.

At the AC place they showed me the little punctures in the wires where PT must have tested them. The owner and the mechanic who had worked on the compressor were really showing me a lot under the hood and answering my questions as to what THEY had done. Though obviously the owner did not do the compressor replacement.

The PT guy had showed me how the cam sensor worked magnetically (and I had saved the old sensor so he could try it, too). He did not give me any detailed printout of what he had done.

We drove to Houston Saturday (and stopped and started a lot of times since we stopped at various places and helped my son move) and it only did the low idle thing once (when my son was behind the wheel to drive us to his new apt. and he started it with me in the passenger seat). When we stopped at a light I told him to turn it off and start it again and it went back to normal.

So, I think my wife is less freaked out by it now, but it does seem to be a strange coincidence if that started only when the compressor was replaced. I asked them at both places if there might be other wires I could not see that might have gotten damaged. The harness to the cam sensor did not look like it had been bumped into during the AC work (or even touched).