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    Thread: VAG-COM procedures for testing the MAF, O2 sensors and catalytic converter

    1. 02-29-2004 01:10 AM #1
      In order to test your MAF, O2 sensors and catalytic converter, check out the following blocks in the "Engine" control module with your VAG-COM. Blocks 002, 030, 032 and 033 are done in "Measuring Blocks" while blocks 036, 034 and 046 are done in "Basic Settings". Let me know if you have any questions about how to run the tests. (NOTE: The following tests are MKIV VR6 specific. If you have a 1.8T or 2.0 engine, the procedure from running the automated tests is slightly different. For a 1.8T engine, see this THREAD for instructions on how to initiate the tests. I'm not positive about the initiation procedure with a 2.0 engine, but from what I've found, with an AEG engine you manually raise the engine speed to between 1800 and 2200 RPMs, and with the AVH and AZG engines, you derpress the accelerator to the WOT (wide open throttle) position to raise the engine speed to ~2000 RPMs.


      Block 002 - Load Registration

      - Check the MAF airflow reading at idle. Make sure the car is running and warmed up and the A/C is off. Go to Block 002 and look in Field 4. The value at idle should be between 1 and 25 g/s. If it's lower than 1 g/s, then there is probably a leak in the intake tubing between the MAF and manifold.


      Block 030 - Oxygen Sensor Regulation

      - Go to Block 030. Field 1 is a three-digit binary code which gives the status of the pre-cat oxygen sensor. Field 2 is the same thing but for the post-cat oxygen sensor. The digits indicate whether or not the sensor heater is working and whether or not the oxygen sensor control is operational and active. The value should fluctuate between 111 (heater on) and 011 (heater off). The last two digits can also fluctuate between '1' and '0', but should be predominantly '1'.


      Block 032 - Oxygen Sensor Control Learned Values

      - Go to Block 032. Field 1 represents the fuel trim at idle (additive) and Field 2 represents the fuel trim at part load (multiplicative), i.e., while driving. The value should be between -10 and +10% (negative indicates the engine is running rich and positive indicates the engine is running lean). If the value is close to +25% (which is the upper limit), it usually means that the MAF is bad. If the value is somewhere betweeen +10 and +25%, it could mean that the pre-cat oxygen sensor is bad, there is a leak in the intake or that the MAF is on it's way out. The value I found for my car (VR6), which has a new 2.0 MAF and new oxygen sensors is +1.6%.


      Block 033 - Pre-Cat Oxygen Sensor Control

      - Go to Block 033. The value in Field 1 represents the pre-cat oxygen sensor control. The value should fluctuate at least 2% in the -10 to +10% range.


      Block 036 - Post-Cat Oxygen Sensor Control

      - Go to Block 036 (this test must be done in basic settings, not measuring blocks). Depress and hold brake pedal to run the automated test. The engine RPMs should raise to around 1400. Field 1 is post-cat sensor voltage. It must fluctuate slightly between 0 and 1V. Field 4 will say either 'TEST OFF/ON' before/while the test is running and either 'B1-S2 OK' (sensor is good) or 'B1-S2 NOT OK' (sensor is bad) after the test is finished. Release the brake pedal after the test finishes.


      Block 034 - Aging of Pre-Cat Oxygen Sensor

      - Go to Block 034 (this test must be done in basic settings, not measuring blocks). Depress and hold brake pedal to run the automated test. The engine RPMs should raise to around 1400. Field 1 is the engine speed. Field 2 is the catalytic converter temp. Field 3 is the value which tells you how aged the sensor is (not sure what it's called). Field 4 will say either 'TEST OFF/ON' before/while the test is running and either 'B1-S1 OK' or 'B1-S1 NOT OK' after the test is finished. The aging value must be above 0.80. The value for a new sensor is 1.99. The value will decrease as the sensor ages. Release the brake pedal after the test finishes.


      Block 046 - Catalytic Converter

      NOTE: The test in Block 034 must be done just before this test or it will NOT initiate!

      - Go to Block 046 (this test must be done in basic settings, not measuring blocks). Depress and hold brake pedal to start the automated cat. test (last approx. 100 secs - the cat needs to be warmed up above a certain threshold for an accurate reading - the threshold is usually 400°C). The engine RPMs (Field 1) should raise to around 1400. Field 2 is the cat. temp. This will also rise during the test. Field 3 is the cat. conversion efficiency. If the cat is good, the value should be below 0.50 at the end of the test. Field 4 will indicate if the cat is good (CAT B1 - OK) or bad (CAT B1 - NOT OK). Release the brake pedal after the test finishes.


      Modified by VgRt6 at 12:24 AM 11-7-2004


    2. 02-29-2004 01:38 AM #2
      Once again you've come trough for us!!!
      You should win some kind of award for all the help you've given...
      My Bro's car keeps throwing codes, and these are the very tests I was gonna do.
      Great help...
      thanks.
      If I knew where you lived I'd send you a or two..

    3. 02-29-2004 09:26 AM #3
      Thanks. I've already posted this in a few other threads, but realized I should just post it in its own thread so that it's searchable.

      Good luck with the tests and let me know if you ahve any questions.

      Gary


    4. Member dragonfli_x's Avatar
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      04-28-2004 10:34 AM #4
      Gary, you got the parameters and steps to check to see if the car is knocking or pulling timing?

      Good looking out, you're still my VR6 hero!

      VRalliance #146

    5. 04-28-2004 10:57 AM #5
      Not off hand, but I can look into it. I know that you can monitor the timing, injector duration, etc in one of the blocks, but don't remember which one off hand. I'll post here when I find out.

    6. Member dragonfli_x's Avatar
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      05-01-2004 01:57 AM #6
      any luck... need to find out if my car is doing weird funky shat around 4500-redline.
      VRalliance #146

    7. 05-01-2004 09:50 AM #7
      Sorry about the delay. I've been really busy dealing with insurance and replacing my wife's car (someone alammed into the back of it and totalled). We got a new Passat Wagon Thursday night!

      I'll go out to the car now, plug in the VAG and see what Blocks you should log.

      Gary


    8. 05-01-2004 10:41 AM #8
      I just hooked the VAG up to the car and checked things out. You should log Block 002 and 003. Here's what that will tell you ...

      Block 002 - Field 2 - Engine Load
      Field 3 - Injector On Time

      Block 003 - Field 3 - Engine Load
      Field 4 - Ignition Timing


      Log these Blocks while driving under the conditions that you notice the problems. If something funky is going on (knocking and ignition retardation), my guess is it would show up in these values.

      Gary


    9. Member dragonfli_x's Avatar
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      05-01-2004 02:29 PM #9
      what would a knocking or retard code look like? any specific values in a general range in these blocks am I looking for when I log them?
      VRalliance #146

    10. 05-01-2004 03:04 PM #10
      Not sure. My guess is that you'd see a dramatic change in the ignition timing value if the engine were knocking. Log the data and plot it. If you notice a big drop in the timing in the problem RPM range, then that's probably indicative of knocking.

      I'd post this specific question in another thread (in the 12v forum)? Someone there should know more about ignition timing.

      Gary


      Modified by VgRt6 at 3:06 PM 5-1-2004


    11. 08-27-2004 07:06 PM #11
      Gary, I just did this test. Everything checked out except Block 046 test came back CAT B1 - Not OK. the value was 0.67.. next steps?

    12. 08-27-2004 08:32 PM #12
      Is your CEL on or did you find code 16804? Sounds like your cat is on the way out.

      How many miles on the car? Hopefully you've got less than 80k.

      Gary


    13. 08-28-2004 01:42 AM #13
      no CEL, no fault codes. I just got this problem when running the cat converter test.

      56k miles. should it be covered under warranty?

      Allan


    14. 08-29-2004 06:58 PM #14
      That's weird that the cat does not pass yet you still have no code/CEL.

      It would be covered under warranty, but I doubt they'd honor it with no reason (CEL or code) to run the cat test. If you can convince them to, then great. If not, just wait until the CEL/code pops up and then take it in. Just make sure you do it before 80k miles comes around.

      Gary


      Modified by VgRt6 at 11:43 PM 2-15-2009


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      08-29-2004 07:49 PM #15
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    16. 08-30-2004 12:32 AM #16
      OK gary, I'll wait to see when the cel pops up then.

      Different car, '00 vr6 automatic:

      getting the following codes:

      16825 - EVAP Emission Control Sys: Incorrect Flow
      P0441 - 35-00 - -
      17545 - Fuel Trim: Bank 1 (Add): System too Rich
      P1137 - 35-10 - - - Intermittent

      Ran the above tests, MAF seems to be working okay, but:

      Block 030 - Oxygen Sensor Regulation test we're mainly seeing 000 with the occasional 100 every so often, both fields.
      B1-S2 OK (block 036 test) after a long wait for the test to kick off, but the block 034 test doesnt seem to want to run. I held my foot on the brake for a good 5-7 mins with it saying "TEST OFF"

      ideas? I should post in the vag-com forum too...



    17. 08-30-2004 08:34 AM #17
      Quote, originally posted by alchu »
      OK gary, I'll wait to see when the cel pops up then.

      Different car, '00 vr6 automatic:

      getting the following codes:

      16825 - EVAP Emission Control Sys: Incorrect Flow
      P0441 - 35-00 - -

      This is almost definitely a leak in the EVAP system, usually due to a broken vac. line or a stuck/broken valve. I'll post the Bentley CD diagnostic steps for the code when I get home tonight.

      Quote, originally posted by alchu »
      17545 - Fuel Trim: Bank 1 (Add): System too Rich
      P1137 - 35-10 - - - Intermittent

      Ran the above tests, MAF seems to be working okay, but:

      What tests did you run? Did you check the fuel trim in Block 032, Field 1? Since you have this code, the fuel trim must be out of spec (too negative).

      Quote, originally posted by alchu »
      Block 030 - Oxygen Sensor Regulation test we're mainly seeing 000 with the occasional 100 every so often, both fields.
      B1-S2 OK (block 036 test) after a long wait for the test to kick off, but the block 034 test doesnt seem to want to run. I held my foot on the brake for a good 5-7 mins with it saying "TEST OFF"

      ideas? I should post in the vag-com forum too...


      That's weird. I'd try running the test again in Block order. I've noticed that the VAG can be finicky sometimes with the order the tests are perfomed or with the conditions that need to be met (the Bentley CD mentions nothing about this though). One time I tried like 5 times to get the cat test (046) to run, but it wouldn't start automatically. I tried again after driving about 15 miles and it worked the first time. Try it again and see what happens.

      Gary


    18. 08-30-2004 03:19 PM #18
      Quote, originally posted by VgRt6 »

      What tests did you run? Did you check the fuel trim in Block 032, Field 1? Since you have this code, the fuel trim must be out of spec (too negative).

      That's weird. I'd try running the test again in Block order. I've noticed that the VAG can be finicky sometimes with the order the tests are perfomed or with the conditions that need to be met (the Bentley CD mentions nothing about this though). One time I tried like 5 times to get the cat test (046) to run, but it wouldn't start automatically. I tried again after driving about 15 miles and it worked the first time. Try it again and see what happens.

      Gary


      I did everything in order as posted above, but interestingly, block 32 didn't give me any bad values. I'll try everything again when my friend brings his car over for an oil filter change.


    19. 08-30-2004 03:30 PM #19
      Weird!!!

    20. 09-10-2004 12:50 AM #20
      I'm getting a 1.06 for my cat numbers.. not a 0.50.. I'm assuming this is bad...

      It does pass the cat test...

      So what does this mean?

      I'm getting error 16804 - Bank 1: Efficiency below threshold (Sporadic)

      It comes and goes.

      All other sensors test fine.

      Car is a 2002 Jetta 2.0 GLS with 130,000 miles.... I drive a hell of a lot.


    21. 09-10-2004 07:25 AM #21
      The 16804 shows up when the cat does NOT pass, so it's strange that it passed when you did it manually. It's possible that it's just starting to fail or there's an intermittent problem somewhere else in the diagnostic circuit that giving a false fail every once in a while.

      It's also possible the the cat test is engine specific. My directions are VR6 specific. I'll check tonight to see if the 2.0L tests/specs are any different.

      Gary


    22. 09-10-2004 07:35 AM #22
      Quote, originally posted by kilgor »
      Car is a 2002 Jetta 2.0 GLS with 130,000 miles.... I drive a hell of a lot.


      WOW! And I thought I drove a lot!

      Gary


    23. 09-11-2004 09:56 AM #23
      the only difference in the procedure is that instead of pressing the break pedal to start the test. You press the accelerator pedal until it hits the floor and presses the solenoid button. It then raises your RPM to about 2k and starts the test...

      it passes all the tests...

      but cat sensor reads 1.06 instead of 0.50.....
      after test is done..




      Modified by kilgor at 2:58 PM 9-11-2004


    24. 09-11-2004 10:10 AM #24
      If you're getting 1.06 after the test and CAT B1 NOT OK, and code 16804, then either the cat is bad or you have a problem with the O2 sensors.

      FYI, there was some type of recall or extended warranty (not sure which, but I think it's probably the recall) on the early MKIV 2.0 cars because of problems with the O2 sensors and MAF. I wonder if it could be related. A search might be helpful.

      Gary


    25. 09-11-2004 04:29 PM #25
      it says :CAT B1 - OK

      after test...

      all o2 sensors test OK... aging is at 1.33 for before cat....
      which suprises me...

      I'll just wait till it becomes chronic... is a 2002 an early MKIV? I had a 2000 MKIV.. but it was a TDI.. I'm thinking I'm going to get another TDI when this car dies. I don't want to have to deal with cat converters and spark plugs, etc... haha

      I posted the 2.0 procedure in the Vag-Com section with credits and kudo's to you by the way...

      Thanks!


    26. 09-11-2004 10:23 PM #26
      Thanks.

      The early 2.0s with the problems were the '99.5 and '00 cars (AEG engine code).

      I'm completely stumped about your test results. Like you said, I wouldn't worry about it until it becomes chronic. Hopefully it won't.

      Gary


    27. Member Fantomasz's Avatar
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      10-23-2004 09:37 AM #27
      Quote, originally posted by VgRt6 »
      The following tests are MKIV VR6 specific. If you have a 1.8T or 2.0 engine, the procedure from running the automated tests may be slightly different. For example, on a 1.8T engine, the tests are not automatically started by depressing the brake pedal. Instead, you must manually raise the RPMs to the noted values using the accelerator pedal. If you have one of these engines, please verify these tests with someone who has performed them on your particular engine before performing them yourself.


      do You know how to check MAF,O2 on 1.8T and 2.0?
      what rpms?


    28. 10-25-2004 09:47 AM #28
      Quote, originally posted by VgRt6 »
      That's weird that the cat does not pass yet you still have no code/CEL.

      It would be covered under warranty, but I doubt they'd honor it with no reason (CEL or code) to run the cat test. If you can convince them too, then great. If not, just wait until the CEL/code pops up and then take it in. Just make sure you do it before 80k miles comes around.

      Gary

      finally got my CEL today...

      16804 - Catalyst System: Bank 1: Efficiency Below Threshold
      P0420 - 35-10 - - - Intermittent

      Is that it? guess I should just make an appointment...


    29. 10-26-2004 09:21 AM #29
      Quote, originally posted by VgRt6 »
      The 16804 shows up when the cat does NOT pass, so it's strange that it passed when you did it manually. It's possible that it's just starting to fail or there's an intermittent problem somewhere else in the diagnostic circuit that giving a false fail every once in a while.

      intermittent seems right. I dropped the car off at the dealer this morning. hopefully they'll honor the 8 year, 80,000 mile warranty. I don't see any reason why they wouldn't...

      -A


    30. 10-26-2004 09:41 AM #30
      Quote, originally posted by Fantomasz »


      do You know how to check MAF,O2 on 1.8T and 2.0?
      what rpms?

      The tests should be the same, but the procedure for initiating them may/will be different. I know on the AEG 2.0 cars you need to manualy raise the RPMs into a specified range and hold there for the tests to initiate and run. The Bentley CD recommends using a stick/rod to depress and hold the accelerator at the appropriate spot.

      I can check about the specific procedures (RPMs) when I get home.

      Gary


    31. 10-26-2004 09:43 AM #31
      Quote, originally posted by alchu »

      finally got my CEL today...

      16804 - Catalyst System: Bank 1: Efficiency Below Threshold
      P0420 - 35-10 - - - Intermittent

      Is that it? guess I should just make an appointment...

      That's the code ... welcome to the club! Hopefully they'll cover it under the warranty. The may insist that you wait until it is not intermittent, but hopefully not.

      Gary


    32. 10-26-2004 02:01 PM #32
      Quote, originally posted by VgRt6 »

      That's the code ... welcome to the club! Hopefully they'll cover it under the warranty. The may insist that you wait until it is not intermittent, but hopefully not.

      Gary

      The service advisor calls me just now and catches me off guard. He says "Hi, there's a problem with your car... and there are a few reasons for what the cause is. Have you done any tune-ups on your car?"

      me: "excuse me?"

      sa: "tuneups.. you change the sparkplugs?"

      me: "sparkplugs, yes"

      sa: "who changed them?"

      me: "I did."

      sa: <covers phone but I hear him say "are they the right plugs?" and the tech reply "yeah">

      me: "they should be OEM plugs"

      sa: "yes.. okay well let me get to the bottom of this. somethings happening and your car isn't burning fuel properly so your catalytic converter is bad.I'll call you back"


      hmm. gary you know any reason why the cat would fail this quickly? 58,000 miles as of two days ago.


    33. 10-26-2004 02:08 PM #33
      Grrrr.

      now he's saying that he's gonna replace the cat under warranty, BUT he wants me to pay for the o2 sensors and labor associated with them. He says "they're not bad, but when we replace the cat converter, we replace the o2 sensors along with it as a maintenance step". He wants to charge me $175 for the o2 sensors and labor associated. I'm unsure how to proceed from here.


    34. 10-26-2004 02:40 PM #34
      Are you comfortabel changing them yourself? They cost about $45 for both. There is a DIY in the my DIY thread for changing them.

      Gary


    35. 10-26-2004 02:50 PM #35
      thing is, I don't think I should have to. All labor associated with changing the catalytic converter should be included. if that means you need to take off the old ones and them on the new cat, I'd assume that the warranty should cover it. And if the dealer thinks taking off the old o2 sensors are too much of a pain, they should replace the sensors themselves. Am I out of line in my thinking?

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