Author Topic: Common Check engine light problems? (Read 9263 times)

Smokey Eddy · « **on:** November 13, 2008, 07:16:26 pm »

I searched and searched and couldn't find a thread on specifically check engine light problems so i figured i'd make one.

I have a 2000 TDI golf that has always gone to the stealership for services. The glow plug light turns off almost instantly when i turn the key to the "on" position. There is no way that they get up to temp in half a second and i recognize that. I checked them all, one was dead - replaced it, but the light still goes off immediately. What is wrong with it? the relay? where is the relay? Is this related to the check engine light? i don't think it is...

the check engine light has also come on recently but i knew the glow plug light has been wrong for months. It still starts instantly and only the dead glow plug was sooty.
Is there a common issue with the "check engine light" ? It comes on almost regularly and my parents have always taken it to the stealership for $xxx.xx amounts of money (lots). Any common checks? a particular sensor perhaps? They don't think i can fix anything (even my own IDI TD) and i want to prove them wrong.

this car was made in Germany, not Mexico (if it matters). Other than the check engine light being on the car has absolutely no other problems now that i changed the GP. It still pulls HARD and doesn't hesitate to get up to speed.

G60ING · « **Reply #1 on:** November 14, 2008, 02:21:25 pm »

You could have a dozen different things wrong with the car. Your best bet is to locate somebody near by that has a Vag-Com cable and take a look at the codes stored in the car or swing by and autoparts store like advance Auto parts and have then scan the car for codes.

Smokey Eddy · « **Reply #2 on:** November 14, 2008, 02:23:44 pm »

Mmmm
someone told me that a bad glow plug could trigger the light to go on. I changed a dead GP but the light is still on.
He says you have to get it "Cleared"
that the dumbest thing ever. What a stupid and cheap way to suck money out of people. I'm guessing the stealership would want like 100$ to "clear" the light.

the caveman · « **Reply #3 on:** November 14, 2008, 03:59:32 pm »

First off, TDI's hardly need glow plug heat to start except when it's actually cold i.e. 40 o F or 5 o C and below.
An engineer i met from VW admitted that the diagnostic for the glow plug circuit is too sensitive. It will set a code if there is a .3 amp diference between 2 or more glow plugs. First off , of course 1 or more bad GP's will set a code. Test them by trying them on a battery, they must all take the same time to get red. When changing one or more make sure all 4 are the same brand -Bosch or Beru etc. Another common problem is the buss bar and how it connects to the GP's . Sometimes putting on a little die-electric grease on the tip of each GP will solve it, while makeing sure the bar is pressed on properly to each GP. The buss bar it self can fail. I have changed many. Another issue to watch for on any mk 4 VW are the grounds. usually if there is only one DTC when checked then it's not a ground . However if after changing GP's and the buss bar doesn't solve the recurring DTC , then check and clean ALL the grounds. Remove the battery and plate , remove the 2 or 3 terminal blocks and the large wire connector. Clean the connectors till they are clean copper and shiny. Reinstall with die-electric grease between each one. The ground at the motor should be done also. Make sure the special bolt that it attaches to is tight. There are also some beside the ECU in the plenum /wiper chamber.

Smokey Eddy · « **Reply #4 on:** November 14, 2008, 04:30:07 pm »

oh wow, thanks caveman I'll do those. Need some dielectric grease first!
But say that solves the problem. Will the light go off by it's self?

Smokey Eddy · « **Reply #5 on:** November 14, 2008, 11:48:22 pm »

Why would you want to use die-electric grease on something you want to promote the flow of electricity to?

What is the purpose behind the die-electric grease?

Doesn't that mean it won't conduct if you put a non-conductive insulator all over it?

jtanguay · « **Reply #6 on:** November 15, 2008, 12:55:15 am »

Quote from: "Smokey Eddy"

Why would you want to use die-electric grease on something you want to promote the flow of electricity to?

What is the purpose behind the die-electric grease?

Doesn't that mean it won't conduct if you put a non-conductive insulator all over it?

as long as the metal is touching the metal you're fine... the die-electric grease really helps cut corrosion! use it on your battery terminals to keep them from going green :lol:

i've tried the conductive grease... that stuff is ok, but what is it made of? i'm sure theres lead in there :roll: :shock: wear gloves!!!

Smokey Eddy · « **Reply #7 on:** November 15, 2008, 05:05:07 am »

Ah right right.
I'll have to do that.

No one has really answered one of my questions directly.

Will fixing this issue with the bus bar and contacts make the light turn off???

I've noticed now that i've changed the dead GP the check engine light doesn't come on for a few seconds. Under a minute for sure but not immediate on start up.
maybe 20 seconds?

Sprockets · « **Reply #8 on:** November 15, 2008, 07:04:10 am »

Ok, to start with, yes, a dead glow plug will cause a CEL, and no, replacing the plug will not put the light out until it is cleared. The reasoning behind the glow plugs is not so much a starting issue, more an emissions thing on a modern diesel. They keep active to increase combustion temp and make cold running more efficient until there is some heat in the engine.

I had a certain 150hp PD engined car go through a lot of glow plugs, but it was running a superchip (so more than likely at around 175hp) and was thinking the temp was probably getting a bit much for them. Tried both NGK and bosch GP.

Anyhow, enough rambling from me.

-Gavin

the caveman · « **Reply #9 on:** November 15, 2008, 02:00:26 pm »

A good die-electric grease has solved so many weird electrical gliches that i now use it where ever i think it'll help. Make sure it's for electrical conductivity.
If you have no way of erasing the DTC your self, it will go off around 50 cycles of the ignition,if there isn't any other DTC.

Smokey Eddy · « **Reply #10 on:** November 15, 2008, 04:24:43 pm »

Quote from: "the caveman"

A good die-electric grease has solved so many weird electrical gliches that i now use it where ever i think it'll help. Make sure it's for electrical conductivity.
If you have no way of erasing the DTC your self, it will go off around 50 cycles of the ignition,if there isn't any other DTC.

50 cycles of the ignition?

ok, so i'll put the die-electric grease on all GPs, all the contacts/grounds and so on.

then cycle the ignition to the on possition 50 times, and then start it?

(it has to be "Air-cared" very soon and they wont even bother doing it if the "DTC" light is on - automatic fail)

Just did the 50 cycles and the light still turns on after almost exactly 30 seconds.

the caveman · « **Reply #11 on:** November 16, 2008, 11:06:41 am »

What i meant about the ignition cycles was that 1 cycle is staring the car cold ,getting it warm and shutting it till it gets cold and repeat. So 25 days of driving to work etc. It may be faster to go to a shop with a scanner and have them erase the fault.

Smokey Eddy · « **Reply #12 on:** November 16, 2008, 10:28:22 pm »

Ohhhhhh
yeah... well the insurance runs out on dec.3

I've given up though. I asked my pops (its his car) if i can do the die-electric grease thing and he thinks im going to break something?

I already changed a dead glow plug which im not going to tell him about. My mom gave me the money for the GP though which was nice. I just love driving it so i don't mind fixing it. My dad is just nuts and paranoid. The car is 8 years old and he still insists on taking it to the stealership. why? because he has no idea what is under that plastic cover that says "1.9 tdi". I just wish he would pay ME half as much as he pays the stealership to do the same job. It's frustrating as hell, especially when you are a poor student trying to rebuild a VW :wink:

what ever... :?

Powered by Spearco · « **Reply #13 on:** November 17, 2008, 01:10:59 am »

Disconnect the battery for 5min. then reconnect it.
If you still have the factory radio, get the radio code "first".
If the radio is a "Monsoon" radio, then don't worry about the code. They have their own memory.
That should clear the codes and reset the check engine light.
Try that.
If you can't get ahold of Vag com. Go to a local parts house and get them to scan your codes. They'll be "P codes", then report back with those. Someone can translate them into VW codes.

Smokey Eddy · « **Reply #14 on:** November 17, 2008, 04:10:56 am »

Quote from: "Powered by Spearco"

Disconnect the battery for 5min. then reconnect it.
If you still have the factory radio, get the radio code "first".
If the radio is a "Monsoon" radio, then don't worry about the code. They have their own memory.
That should clear the codes and reset the check engine light.
Try that.
If you can't get ahold of Vag com. Go to a local parts house and get them to scan your codes. They'll be "P codes", then report back with those. Someone can translate them into VW codes.

ok im sorry. "Vag com" and "get the radio code "first"" and ""Monsoon" radio"
is all a foreign language to me.

it still has the factory radio in it. Do i still disconect the battery?
What on earth do you mean i have to get the code "first" i have no idea what you're talking about.

You really have to talk to me like a real idiot because i don't speak ecu talk :oops:

I really appreciate your help. what you said is probably a solution i just don't understand what you're saying.

What i understood is ... disconnect the battery for 5 minutes so the capacitors or what ever can drain out (like in a computer). then turn the car on and the light should be off?
the part about the radios im totally clueless....
and then if i still get the engine light i can go to a shop and ask them to tell me what the code is, tell you guys what they told ME and then you'll know what the actual problem is!!!