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'98 Taurus Code PO340 (Cam Shaft Sensor)


mcconnc
01-20-2005, 02:02 PM
I am in dire need of help. '98 Taurus (72k miles-maintained excellently), I've had many issues outside of normal wear & tear w/ it of late. First, had code PO412, had it fixed, cost about $90. Drove away from service station, engine light came back on. Brought it right back, code PO340-Cam Shaft Sensor, they replaced the cam shaft sensor for $100 and off I went. They said I'd be fine. Within 4 days, engine light back on, PO340 again! Brought it back, they looked at it for days, and said they didn't know what more to do, everything had been tested and seemed fine. Of course they wouldn't refund me any of the money I'd spent there. Then I brought it to my hometown Ford master gooru mechanic (200 miles away) who just opened up his own shop after running 2 Ford dealership service departments. He tested the heck out of it, and said the cam shaft sensor was good, and the only thing it could be was the computer (PCM). Now mind you, this was in December, of course when my inspection was about to run out and w/ new NY laws, I would definitely fail. So we replaced the computer ($320 on 12/10/04) and drove it for a couple weeks and retested it. No codes!! I passed inspection!! Yeah. On 1/5/04, transmission blew. Only 72k miles, so I decided to have it rebuilt at AAMCO. $1,700 later, I had my newly improved Taurus on 1/14. It seemed to run excellent, better than ever before. Then yesterday (1/19), engine light back on. Took it back to AAMCO, it is PO340-Cam Shaft Sensor again. I'm stumped. My hometown Ford gooru mechanic is stumped as well. He said could possibly be the "drive" thing near the sensor. I'm just a beancounter, so not up to speed on mechanic lingo. If anyone has had this issue or has any suggestions, I'd greatly appreciate it. I love the car, but I've put over $4k into it the past 6 months and am getting tired of the issues. Thanks for any input.

lee308
01-20-2005, 02:40 PM
Just an idea, but, if it runs ok, and you've passed the state test, just drive it with the engine light on. My dad has a 95 taurus that has had the engine light on since 2000. He said he would worry about it if it stopped. he put a piece of tape over the light so it would not bother him at night. That was about 70k miles ago. PS, no state emissons test here.

yotermanic
01-20-2005, 11:26 PM
Did they replace the sychronizer with the cam sensor? I always do them in pairs, because they usually go out that way. The sychronizer acts as a distributor kind of, except it spins a small metal shutter in front of the cam shaft sensor, which uses a magnet to read when the shutter is passing. This is probably the drive componant he was referring to and I wouldn't hesitate to say he's probably right.

mcconnc
01-24-2005, 06:07 PM
Did they replace the sychronizer with the cam sensor? I always do them in pairs, because they usually go out that way. The sychronizer acts as a distributor kind of, except it spins a small metal shutter in front of the cam shaft sensor, which uses a magnet to read when the shutter is passing. This is probably the drive componant he was referring to and I wouldn't hesitate to say he's probably right.


No they did not. I will have them look into that. If it is the sychronizer can the car eventually break down if I don't fix it soon? I want to be 100% sure that will fix the problem once and for all before I have it done. Thanks for the input.

TomV
01-26-2005, 09:16 AM
I had my sensor break and had the magnet fall into the synchronizer where the vane was then mangled. My Check Eng Lite was on for months but I noticed no degradation in performance or gas mileage.

Others have stated that engine performance suffered. If that is your case then repair it soon.

The only reason I repaired it was to pass our emissions test here in Maryland.

rjs985
02-12-2007, 04:47 PM
No they did not. I will have them look into that. If it is the sychronizer can the car eventually break down if I don't fix it soon? I want to be 100% sure that will fix the problem once and for all before I have it done. Thanks for the input.

Very curious! I have the exact same problem. I tested the CMP (camshaft position sensor) per the service manual, I found no problems and even replaced the CMP for $16. The CEL comes back on after the second resart of the engine. I looked at the synchro and the vein is in good shape and looks just like the replacement at Napa. I even verified that it is moving. There was no visible damage to the CMP either. I am about to replace the PCM, but still have some doubts.

tomfitzy
08-05-2007, 01:43 PM
I have the same problem with my 99 contour, let me know if you find out the problem.

Dave_s
08-05-2007, 02:01 PM
I'm not sure if it would throw the same code, but are you sure it is installed properly? It could be out of sink (sp?).

rjs985
08-06-2007, 05:24 AM
Update: After troubleshooting the wiring harnes, per the "Ford" instructions from alldatadiy.com, replacing the camshaft position senesor and the PCM, I passed the car on to my cousin who is a mechanic. He followed the same procedures, with the same results. The check engine light never cleared. The car was passed to a local garage who, idependantly, followed the same troubleshooting methods with the same result. They thought it was a PCM problem. My cousin then informed them that the PCM was just replaced, in an atempt to fix the same problem. They were stumped. They are now trying to track down some "electrical issue". They did get the check engine light to stay off long enough for th ecar to pass inspection and then come back on in a day or so. But so far everyone is stumped. At least we have some time to troubleshoot the proble, further. They are looking at replacing tha alternator.

How fun!

USNRET
03-09-2008, 11:10 AM
Hello,

I had a very simular problem, except that the "rotor" would break within a day or two. When this happens, the engine reverts to a default mode for fuel timing, and the engine should run fine. In fact there is some evidence that the mileage is better and that it will run cleaner, but you won't pass smog with the check engine light lit, or the PO340 code set. I took it to a dealer :naughty:and they told me that the syncronizer was bad. To top it off they told me that they have done this replacement many, many times! But according to Ford, there is no recall on this! Anyway $500.00:crying: later it was fixed and worked fine. If your mechanicly incilned, you may be able to replace it yourself. as it serves much the save purpose as a distributor shaft. Good luck!

Fordhcw
03-19-2008, 02:52 PM
I have a 1998 Taurus Wagon with the 3.0L V6 Vulcan engine, which only in cold winter weather gets an intermitent check engine light and a code for the camshaft position sensor. The CMP sensor for the 1998 Vulcan is the two pin type, rather than the three pin type as shown in aftermarket repair manuals. So, if the syncronizer assembly is replaced, a different alignment tool is needed than for the 1996 and 1997 Vulcan. For the Vulcan 1998 to 2001 the Ford Global part number is 303-589 and the OTC part number is 6473. The alignment tool is not needed if only the CMP sensor is replaced and the syncronizer is not moved or rotated or had a loose retaining bolt. As this Taurus is high mileage, it could be in the wiring. Perhaps in cold weather the wire insulation is stiffer, which would cause a weak wire to intermitently fail, as the broken strands loose contact from vibration and road shock. I bought the CMP sensor and the alignment tool in case this problem becomes continuous. That after market repair manual has the typical wiring diagram for the three pin CMP sensor.

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