A4 threw an engine light on way home

[MukGyver]

What is the easiest quickest way to pull the code. Can I use a regular OBD2 scanner? I know I need to invest in a VDCS but I'm just looking for the easiest way to know what code was thrown. All the vitals seem fine and it is running normally and I need to drive this to work tomorrow. My work buddies have OBD2 scanners... if it they work to pull codes. thanks fir the help

edit: I did pull the egr connector about 2 weeks ago and have driven about 250 miles since with no light. until today. would egr code delay that long in coming on?

 

[Mozambiquer]

A regular obd scanner will read emissions related codes, and many engine related codes, but many other codes and anything with the other systems of the car won't be able to be read. Some scan tools won't even work though. We have a snap on scanner at work that doesn't even have volkswagen as an option.

 

[Vince Waldon]

And yes, it's probably an EGR code, which a generic OBD2 scanner will detect. Was going to come on eventually.

 

[MukGyver]

Ok, that's what i'm gathering from reading around. So I'll try an OBD2 tomorrow for shoots and giggles and see if it even connects. Meanwhile, am I going about this right..... I'm looking at the Ross Tech VCDS Lite for my 2004. Could I get the Lite and a Vag-Com interface cable and be set... or is that not enough to see the systems? It's a little confusing all the choices. thanks

 

[MukGyver]

And yes, it's probably an EGR code, which a generic OBD2 scanner will detect. Was going to come on eventually.

I should have said I reconnected it 5 minutes later. I just wanted to take the egr off and look inside the egr cavity. Then reconnected.

 

[Nevada_TDI]

If you get VCDS lite and want all the options, that won't happen as far as I remember. You need to get a knockoff cable, hopefully it works, and you spend $100 on software and registration. By the time you are done, you will wish you had spent the $199.00 at Ross-tech, for a
genuine cable and update-able software, and the option to test cars newer than 2004. Just my 0.02

 

[Vince Waldon]

I should have said I reconnected it 5 minutes later. I just wanted to take the egr off and look inside the egr cavity. Then reconnected.

Ah, ok, well then likely not related, unless the connector has wiggled loose or something.

A scan will tell the story.

 

[Tdijarhead]

Read the code with the generic scanner then go here and scroll through the eight pages of codes to find the one that came up.

Category:Fault Codes - Ross-Tech Wiki

wiki.ross-tech.com

 

[MukGyver]

A knockoff cable doesn't sound like the way to go.. thanks for the heads up. And thanks for the encyclopedia of codes tdijarhead.. WOW now that is a list! It doesn't appear they could have made these cars any more complicated if they tried.

I'll see if the basic scanner will connect today at work. And hope I'm okay driving it. I'm assuming the water and oil vitals etc are on separate warning lights. I didn't even have time to scan the owners manual last night.

update: A relief it ran fine 33 miles to work! Now to find out what ingredient it thinks is missing or wrong.

 

[Mozambiquer]

A knockoff cable doesn't sound like the way to go.. thanks for the heads up. And thanks for the encyclopedia of codes tdijarhead.. WOW now that is a list! It doesn't appear they could have made these cars any more complicated if they tried.

I'll see if the basic scanner will connect today at work. And hope I'm okay driving it. I'm assuming the water and oil vitals etc are on separate warning lights. I didn't even have time to scan the owners manual last night.

Yes, the water and oil vitals are on different warning lights.

 

[MukGyver]

Mass Air Flow P0101 code came up. Do I need to troubleshoot to determine if it's bad .. or is P0101 usually a symptom of something else that needs maintenance? .. Also, does anyone know of any free-pdf repair manuals out there on line, or are there ones for purchase only? thanks

I think I still have a half can of MAF cleaner. could try that

 

[Vince Waldon]

Our MAFs are a hot-film type and generally considered to be tricky at best to not make worse by spraying 'em with something.

A MAF code can mean a bad MAF, but as you point out it can also simply be the sign of it doing its job in detecting airflow that doesn't make sense to the ECU. One of the more common reasons this might happen is a disconnected EGR.... was the engine ever run without the MAF connected?

 

[Mozambiquer]

One other question I would have is if you have an aftermarket air intake?

 

[MukGyver]

Thanks for explaining the hot film type MAF rather than heated resistor type. I'll be careful not to use the MAF cleaner. Would probably make a nice "goo" out of the film.

Vince you mention some type of air flow the ECU might not to make sense of. there is a "stumble" or "hiccup" usually felt when climbing the hill coming home at around 2500 rpm=. It feels almost like a misfire, but softer like an "airflow disturbance" or fuel disruption maybe. could be the ECU finally got bothered enough by it. For the most part it runs great. It gets great mileage so I can't imagine things are too far off.

The air cleaner is stock, K & N, and other than that everything else stock with egr still hooked up. I did do a "cat-thru" about 500 miles ago which seemed to help it breath a better. Maybe that caused the ecu maf flow detection. The code was erasable with the obd2 reader, so I'll try a few things before buying a MAF sensor. It could be the previous owner "over-oiled" the filter so I will clean it & reoil it.. and see if the code comes back.

 

[Tdijarhead]

Likely the K & N is the problem. They don't play nice with this type of MAF. Put the stock air box back in clear the code and see if it returns, I have a suspicion that you'll need a new MAF because of the K&N.

 

[Vince Waldon]

Yup, oiled air filter like K&N not stock, frequent cause of hot-film MAF contamination.

 

[MukGyver]

Makes perfect sense to me. I'll see what happens and get back. thanks! I suppose the ecu confusion over the MAF readings could be sending strange signals to the fuel delivery causing the hiccup on hill climbs too.

 

[Vince Waldon]

Yup.

If your can of MAF cleaner is specifically for hot-film MAFs and you're thinking the MAF is likely already busted... can't bust it more by attempting to clean it.

 

[MukGyver]

Well I've just read lots of information out here on the Tdi site about cleaning hot wire and hot film MAF's and it seems there is a mix of opinions. Both sides of which seem to come from credible tdi veterans. Like you said Vince it's probably not functioning with the oil on it now anyway so it won't hurt to give it a try with the CRC sensor cleaner I have,.. and replace the filter with stock material type filter. thanks again all for the feedback

 

[Mozambiquer]

That's a very common issue when people put an oiled air filter on a tdi. I have seen it many times, whether it's a cone type or K&N stock type. The oil doesn't play well with the maf sensor.

 

[Vince Waldon]

One last hint which you're probably already aware of: the code will not go away even if the issue is resolved... it will need to be reset with a scanner.

 

[MukGyver]

One last hint which you're probably already aware of: the code will not go away even if the issue is resolved... it will need to be reset with a scanner.

The obd2 scanner I borrowed today worked to erase the code and engine light went off. I figured I would clean the maf, replace the air filter and erase the code... in that order. Is that what you're referring to as "resetting" the code? Just want to be clear, thanks

 

[Vince Waldon]

Yup...you got 'er.

The main thing is that once a code gets set for the most part it stays set, even after the issue has been fixed. This sometimes confuses people "I replaced the bad glowplug but the code didn't go away".