All,

My car is 2004 A4 3.0Q. I replaced all 6 spark plugs (stock NGK) and coil packs (STI coil) today. Everything went well and the car runs fine without CEL. Later evening, I was about to go out and when I start the car there is a battery icon stays on. I checked the manual it says Generator Warning Light.

Well... it doesn't stay on all the time; it disappears as soon as I step on the gas. If I turn the car off and re-start right away, it won't stay. It stays on only when I park the car for a while. But it disappears right after I step on the gas.

Could it be my battery is too old? The battery is still original. Could it be the new coils caused the problem?

Thanks for your help.

 

OK.... I did some research and checked the battery. From the "magic eye", it looked dark (no color at all). I remembered last time I checked was still green.

Could it be the battery issue? If so, where can I get it? Does Costco sells it?

Thanks.

 

It's possible you need a new battery, it's old enough, although the light indicates low charging output from the alternator, not necessarily a bad battery. As long as it goes out right away, I would just watch it, and have the charging system checked next time you have the car in for service.

 

Go to a parts store, they can check battery health and the alternator.

 

I replaced the battery today and didn't fix the problem. I checked the voltage today... it seems when I start the engine and let it idle, the alternator won't charge the battery (the indicator lights up and stays on).

If I step on the gas and rev it to 2000rpm or above, the indicator disappeared and alternator starts charging. For some reason, the alternator needs that little kick in order to charge.

Could it be the new ignition coils cause this issue? Or just simply because the alternator is old.

Thanks for your help.

 

pull the alternator, its not that difficult. take it to the parts store and have it bench tested. id bet thats it.

 

Just to give an update on this issue... I swap the new coils with old ones and the problem goes away. When I put the new ones back, I am having the same issue. I am pretty sure it cuased by those new STI coils.

I am running with old coils right now. So far so good. I should purchase stock Audi coils in the beginning.

 

STI coils from a subaru?

 

Not sure if they are for Subaru but I know lots of Subbies are using STI coils. I purchased them from AutohausAZ.com and coils were listed as for my model (I specified for 2004 Audi A4 3.0 quattro). I can't tell if those coils are use more current or not but they definitely use incorrect current which triggers Generator Warning Light.

Ever since I re-installed old coils back, I haven't get any indicator yet. I just hope AutohausAZ let me return them since they don't fit my car; but I already used them for couple days.

Anyway, I just wanted to provide this info to others on the forum. Be aware of STI coils, it may cause some issues.

 

Just read your question again, sorry I mis-understand in my previous post. No, they are not from Subaru WRX-Sti. STI is the brand name.