Can a basic OBDII clear codes?

morris1524 · Post by **morris1524** » Sat Apr 26, 2008 1:18 am

I have a 03 Jetta TDI Wagon. Recently, I have had an outbreak of check engine light coming on. The guy at the shop who has been clearing it is getting tired of it. It has 70K on it.

Several times it gave the code: Literature. Then, it gave glowplug #3. Then it was fine for a while, and now has come back on again.

If I get a hold of a basic OBDII, will I be able to clear it?

Also, how long do the glow plugs last? Should I just change them, to see if that keeps the light off?

caveman · Post by **caveman** » Sat Apr 26, 2008 12:46 pm

TDI glow plugs are easy to check. Use a 12 v test light , carefully pull off the buss bar to the glow plugs, and connect the test light to the positive of your battery. place the tip of the test light to each glow plug tip. It should light up. If it doesn't, that plug is shot. If your mechanic has already done this, then it's probably the buss bar itself, although they have a habit of coming loose. If you took it off to check the plugs or not, push down on each connection to make sure it's sitting right. If they were replaced in the past it may be that one is a different brand than the others. They must all be the same- Beru or Bosch. TDI glow plugs last way longer than DI ones.

morris1524 · Post by **morris1524** » Sat Apr 26, 2008 7:25 pm

Caveman,
Thanks for the details on how to test the glow plugs.

I will do that.

Let's assume I find one is bad. I replace them all, right?

Then, would a basic OBDll work to reset the check engine light?

caveman · Post by **caveman** » Sun Apr 27, 2008 10:28 am

I wouldn't bother changing the rest. TDI plugs last way longer than DI ones because the light up time is much less. I would remove them to make sure they are all the same brand and when they're out you can test them on a battery, but if the others are okay ,put them back

MayorDJQ · Post by **MayorDJQ** » Fri Jun 06, 2008 9:33 pm

Using a test light won't tell you if a plug is marginal. You need to use an ohmmeter to really check them. If one is shorted to ground, a test light will light up.

The harness is very susceptible to corrosion. Try cleaning the contacts inside each of the plugs on the buss bar and the electrodes on of the GPs.

Using an ohmmeter, test from the tip to the part where you'd apply a wrench to remove the plug. The resistance should be between .5-1.2 ohms. If they're within .2-.3 of each other, they're good.

coke · Post by **coke** » Fri Jun 06, 2008 10:08 pm

My father's TDI glow plugs died at 100k miles, kept throwing up glow plug codes. He replaced the harness before the plugs, still threw up codes, so he swapped in brand new Bosch and used his copy of Vag-Com and cleared them. No problems since.

I don't necessarily agree with the statement that the TDI plugs last longer because they dont stay on as long. I was under the understanding that they actually stay on after startup to aid with cold running for up to 3 minutes.

I may be wrong though. Its happened before.

Bubba1 · Post by **Bubba1** » Sat Sep 06, 2008 4:47 pm

the alh has the glow in the coolant passage by the head ,right?The cylinder plugs glow after start up too?Thats seems excessive.

MayorDJQ · Post by **MayorDJQ** » Sun Sep 07, 2008 9:46 am

Bubba1 wrote:the alh has the glow in the coolant passage by the head ,right?The cylinder plugs glow after start up too?Thats seems excessive.

ALH engines have GPs in the head just like any other VW Diesel. They will stay on after start up to help cut down emissions.

ALH cars with a manual transmission have 3 glow plugs in the water outlet on the head, but they don't really do too much when it comes to warming the car up.

vw_commuter · Post by **vw_commuter** » Sun Sep 07, 2008 10:14 am

To answer the question of the post, yes, an OBDII scanner can clear codes and reset the CEL.