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    Thread: Fault code 16725 - cam position sensor

    1. Member silentsee4's Avatar
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      02-21-2009 07:09 PM #1
      i have replaced the timing sensor twice, along with the cam gear (because i bent the timing part of it) and still am getting the error code 16725.
      wtf is wrong with my 2.0? other than being a 2.0
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    2. Member silentsee4's Avatar
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      02-21-2009 09:31 PM #2
      bump for some1 with knowledge
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    3. Member silentsee4's Avatar
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      02-21-2009 11:13 PM #3
      bump for knowledge
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    4. 02-21-2009 11:38 PM #4
      The cam. pos. sensor is a hall effect.
      3 wires
      -power
      -ground
      -signal
      -verify voltage and ground at connector (refer to schematic for wire configuration) with volt meter.
      -verifiy square wave / signal at same connector with a graphing meter (or a homemade 5volt led test light) DO Not use a conventional test light
      If power or signal problems are present, check at ECM side for open wire or ECM problem.

    5. Member silentsee4's Avatar
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      02-22-2009 03:04 AM #5
      i did actually do a voltage check and it was getting power. what is this square wave thing your talking about?
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      02-22-2009 01:34 PM #6
      Quote, originally posted by silentsee4 »
      what is this square wave thing your talking about?

      Quote »
      A square wave is a kind of non-sinusoidal waveform, most typically encountered in electronics and signal processing. An ideal square wave alternates regularly and instantaneously between two levels.
      http://en.wikipedia.org/wiki/Square_wave

      You usually use an oscilloscope to measure the performance of the sensor. I believe that the output should swing between gnd and nearly 5v.

    7. Member silentsee4's Avatar
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      02-22-2009 10:16 PM #7
      ok, and then from left to right in this picture of the plug which of the 3 holes is which?
      and to do these two tests that are there for me to perform, which of these holes do i test?


      thanks for your help guys, and gals. this all started as a simple cam install for me, and then snowballed into this huge and stupid CEL problem.
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    8. Member silentsee4's Avatar
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      02-22-2009 11:36 PM #8
      so i tested all of the female connectors and these are the numbers that i got. since i dont know which is which i simply tested all with a voltmeter
      for these little diagrams the parenthesis represents the curved side of the connector, uppercase O's are the tested ports and lowercase o's are the ones left alone.
      (_O_O_o_| 12.6
      (_o_O_O_| 7.7
      (_O_o_O_| 5

      i really don't know what I'm doing so bare with me please
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    9. Member silentsee4's Avatar
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      02-23-2009 04:55 PM #9
      blump
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    10. Member silentsee4's Avatar
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      02-23-2009 11:18 PM #10
      dump
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      02-23-2009 11:41 PM #11
      If you can probe the middle wire while the connector is connected you're looking for a square wave output. If you have a multimeter you can check the middle pin for DC to ground but the meter probably won't react quickly enough to give an accurate readout so just look for it to change states rapidly. If not look for positive DC on the + pin and ground on the - pin. Troubleshoot from there. I'm not sure but I wonder if you can pull the sensor, turn the key on, and then monitor the center pin. All you have to do then is swipe a magnet over the sensor and see if it changes states. Just a thought.


      Modified by mcoomer at 4:48 AM 2-24-2009

    12. 09-23-2009 08:11 AM #12
      What were the running problems with the 2.0l with DTC 16275 camshaft position sensor
      range/performance? I know that the CEL is on but does the car show any seroius
      functional problems? Also, what was the fix for your car?

    13. 09-23-2009 10:47 PM #13
      I fixed almost all the problems with a new throttle body and a good used air flow sensor.
      However, DTC 16725 remains and interestingly throttle body adaptation ran to OK on this 2.0l
      99.5 Jetta with an AEG code engine. My local VW dealer tech said he has seen no starts
      with 16725 but this Jetta starts well and only has a poor throttle response to more than a quarter throttle opening. This Jetta will reach and maintain freeway speeds if accelerated gradually.
      With 183,000 miles on the odometer I am thinking the catalytic converter is partially plugged. Has anyone else had a similar experience with a 16725 DTC on an AEG 2.0l engine?

    14. Forum Sponsor Dana @ Ross-Tech's Avatar
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      09-24-2009 08:12 AM #14
      Peter,
      From my experiences with 16725 on that style Cam. position sensor:
      -Bent / damaged pick-up on camshaft sprocket. (a result of tampering or forcing it)
      -Faulty sensor
      -Faulty wiring
      -Incorrect valve (mechanical) timing. This includes damage to the cam. at the key way location and the actual belt timing possibly off a tooth or so.
      I have never seen a faulty ECM cause this, but it is possible.
      http://en.wikipedia.org/wiki/Hall_effect_sensor
      http://wiki.ross-tech.com/inde...00833
      Also see the link Bruce found http://en.wikipedia.org/wiki/Square_wave

      Do you have a graphing meter or oscilloscope? This will be necessary to see the actual signal from the CPS.
      Dana Marie

      P.S. No Scan = No Soup

    15. 09-24-2009 08:18 AM #15
      Does a 16725 DTC on an AEG 2.0l 99.5 Jetta cause a driveability problem?

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      09-24-2009 09:36 AM #16
      Yes it can cause a drive-ablity problem due to being in a fixed timing map.
      Verify your timing is correct.
      As what Dana said above is right on . Also check the key-way on the crank to key-way on cam for damage. If your marks line up.
      It is most likely that something is out of correlation but could also be a sensor, reluctor air cap incorrect, or damaged harness issue or bad ECU.
      Best,
      Jack

    17. 09-25-2009 09:55 AM #17
      Do you know which display group the 99.5 AEG code 2.0l Jetta uses for ignition timing mapped values? The one VW factory manual I have for an AEG 2.0l does not include a procedure for checking ignition timing control. For AAA 2.8l VR6 engines display group 10 shows the mapped ignition timing values but I don't know if the AEG 2.0l uses the same group. Also it was curious that throttle body adaptation ran to OK with the 16725 DTC always present. I thought that all DTCs had to be corrected and cleared before the adaptation of the throttle would run correctly.

    18. Former Advertiser
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      09-25-2009 10:42 AM #18
      No the ADP can fail on some cars and even pass readiness monitors.
      Separate function.
      16725 code has nothing to do with the ADP of TB.
      The information for timing is in the factory repair manual for AAA and AEG
      Also Vag-Com labels the channel and displays a spec in the balloon so you don't have to go hunting through the repair information.
      Best,
      Jack

    19. 09-25-2009 08:15 PM #19
      My question on mapped ignition values for the AEG 2.0l is exactly because that data is not included in the factory repair manual W42 008 198 103 Edition 01.98 that I have. The mapped values are included in the 2.8l VR6 repair manual for the AAA GTI/Golf/Jetta. VWs service manuals are far from complete and I am not describing the Bentley version but the expensive multi-volume sets issued by carline.

    20. Former Advertiser
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      09-26-2009 02:23 PM #20
      Peter,
      What your asking for is for a test that was originally for ABA and AAA engines which use 259 series Bosch ECU's for OBD2.
      The old ECU's you did a test in 010 and then 045-046 for knock
      Then Cabrio late had its own in 022-023 for knock and these Ecu's were a transition into the four body but also had a ABA and A3 chassis.
      The ECU for an AEG is 018 and never supported this test. To my knowledge described as Ignition timing control checking being specific.
      It supports the test in a different way combined with knock control.
      01-04-028 test verify and further for vehicles 98> with some ECU's also having variable cam shaft control. example 094-096 tests for cam control. There are other channels for additional tests with bin bits.
      You can always verify CF of each cylinder in Vag-Com to see whats going on.
      Just because a specific test existed in a old car doesn't mean it will be used in a different fuel or ignition system.
      The test does exist, just a different way.
      Best,
      Jack

    21. 09-27-2009 01:48 AM #21
      Thanks for the explanation. Do you know if for the 99.5 Jetta 2.0l AEG engine if a 16725 DTC
      can under certain conditions send the ECM and /or throttle control module into the emergency running mode? The owner of this 99.5 Jetta cannot afford to replace the camshaft position sensor and is driving the car with a 16725 DTC present at all times. Most of the time the Jetta runs and drives satisfactorily (actually drives pretty well for 183,000 miles Charity Motors car) but occasionally the Jetta will exhibit a severe driveability problem with no ability to develop any engine power. The DTCs at that time are throttle control module related even though there is a new throttle body with clean grounds and proper supply voltage. The problem is intermittent and cannot be reproduced with any degree if regularity--it just happens under very different conditions.

    22. Banned rodgertherabit's Avatar
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      09-27-2009 02:51 PM #22
      Hate to drop in on all of this heavy lingo, but I am having this problem on my vr6 and too am trying to reslove the issue.
      The time i notice is most is on startup. It smells very rich. The car has trouble idling andgod forbid I press the accelerator! haha The rpm's will dip to 3-400.
      Also from reading the posts it sounds like this seems to be more of a throttle body and ecm problem as opposed to a faulty sensor? I mean correct me if I'm wrong.
      [IMG]http://**********************/smile/emthup.gif[/IMG]

    23. Former Advertiser
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      09-28-2009 09:36 AM #23
      Peter,
      Please post an auto-scan at this point.


      Modified by vwemporium at 9:42 AM 9-28-2009

    24. Former Advertiser
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      09-28-2009 09:41 AM #24
      Post an auto-scan please.

    25. 09-28-2009 01:52 PM #25
      The owner has the 99.5 AEG 2.0l Jetta (aka Jetta from hell) for now. No doubt I will see it again!

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