# Check engine light is on 05 VW Passat V6



## mike3366 (Sep 25, 2008)

Hello, I have a 2005 Passat GLX V6 4motion. I just had the engine light come on while driving home (the "MIL" light or whatever they call it). It's not blinking or anything, it's just on. And I was wondering if it's serious or not? I feel absolutely nothing wrong with my car. A couple days ago my mom did accidentally fill it up with 85 octane gas (it needs 87 or more), but we called a mechanic and he said that it's not a big deal. I popped the hood and noticed that the coolant level was below minimum, but if that was the problem, then wouldn't the coolant light come on in the dashboard? Can I continue to drive the car or should I take it to a mechanic?
Thanks in advance for your help.


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## AvantBoy19 (Aug 5, 2005)

*Re: Check engine light is on 05 VW Passat V6 (mike3366)*

It could have been a simple misfire from the lower octane gas. Your ECU learns your driving patterns and when you lower the octane rating sometimes the computer doesnt compensate for the 87 octance, becuase it has been used to running on 91+. It is a quite common thing to happen on VW / Audi's. Usually happening on accelleration or long decel coasts when your foot is off the throttle. 
if you have the code i can tell you exactly what is wrong with it and how to fix, if there is a problem.


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## mike3366 (Sep 25, 2008)

*Re: Check engine light is on 05 VW Passat V6 (AvantBoy19)*

Ok, well the codes are P0491 and P0492, the chick at Autozone said each one came up twice. It could also be P491 or P492, because they just added the zero in their computer. But they said that the codes are not in their system. The little tester computer thingy also read out "secondary air system" for both codes. So what is it? Is it urgent? Thanks for the help man.


_Modified by mike3366 at 5:20 PM 9-25-2008_


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## AvantBoy19 (Aug 5, 2005)

*Re: Check engine light is on 05 VW Passat V6 (mike3366)*

P0491 16875 Secondary Air Injection System Insufficient Flow Bank 1.
P0492 16876 Secondary Air Injection System Insufficient Flow Bank 2. 
That system usually only runs for about 1-2min at cold startup. You may check you combi-valve ( similar to EGR ), and check the vacuum lines and check valves on top under engine cover near firewall. 
Thats all i can think of for now. Good Luck http://****************.com/smile/emthup.gif


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## spitpilot (Feb 14, 2000)

*Re: Check engine light is on 05 VW Passat V6 (AvantBoy19)*


_Quote, originally posted by *AvantBoy19* »_P0491 16875 Secondary Air Injection System Insufficient Flow Bank 1.
P0492 16876 Secondary Air Injection System Insufficient Flow Bank 2. 


First off this is just an auxillary system to "light the cat conveters off" quicker on cold start to get better emissions test performance, so you can drive the car with no worries. The system consists of a pump, a vaccum valve that opens two "Kombi valves" and some plastic piping to carry air flow from the pump to the Kombi valves. Since both banks aren't flowing...I'd suspect either the pump (do you hear any distressing sounds only on cold starts?) or more likely the vaccum control...There are a "zillion" little vaccum lines on top of the engine that control stuff..Kombi valves included..if one of these lines is cracked from the heat...no vaccum..Kombi valves dont' open..no flow...check vaccum lines first..VW has a kit for the V6 motor that replaces the elbow connectors for the kombi's and the hard plastic lines..you need about 2 meters of 3mm vaccum hose (dealer sells by the meter) to replace all the little hoses on the car..do 'em one at a time so you dont mix up connections..gets a bit complicated up at the vaccum solenoid panel in the rear of the engine on top..bet that fixes the problem! Worked 4 me!


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## mike3366 (Sep 25, 2008)

*Re: Check engine light is on 05 VW Passat V6 (spitpilot)*

Ok, thanks for your help guys. I'm not a total idiot when it comes to cars, but I just don't have the skills or experience to be doing this myself. I guess I was just hoping it was something simpler, lazy me, lol. Would you guys have any idea how much it would cost to fix this at a dealer? (Or should I just go to some mechanic?).


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## spitpilot (Feb 14, 2000)

*Re: Check engine light is on 05 VW Passat V6 (mike3366)*

If you have to take it to a shop..take a copy of my post along with you...so you point them to check the vaccum system first! Shops that dont' know these cars well could ez start out thinking its the expensive stuff like pump and Kombi valves and start replacin them when you don't need to. Here's the list going from least expensive to most on this system:
vaccum hoses and little rubber fittings....you could do this if you can stand to get your hands dirty a bit.
vaccum valve (electric valve that turns on vacccum) its up on the "vaccum solenoid/valve board on very top of engine at rear.
Pump
Kombi valves.
This system isn't hard to trouble shoot, but you need to have some good trouble shooting skills..something that many shops not specializing in Audi/VW cars won't have...dealers will..usually...but they charge big bucks for labor ($130/hour here) and parts (list + 25%!







) so you really get #@[email protected]$%%ed taking it in to them out of warranty!


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## mike3366 (Sep 25, 2008)

*Re: Check engine light is on 05 VW Passat V6 (spitpilot)*

Ok, I do hear a sound coming from under the hood on the passenger's side when I first start the car in the morning. It's not loud, more like high pitched, but it doesn't sound normal. So that means it's the pump itself then? How much would the pump cost (just the part)?
Also, could this have anything to with the A/C? A week or so ago, the A/C stopped blowing cool, we took it to a guy and he replaced some kind of temperature sensor. He said that the sensor was prematurely shutting off the compressor. But I noticed that the AC stopped blowing cold again, although I'm not sure if this happened before or after the light went on.


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## spitpilot (Feb 14, 2000)

*Re: Check engine light is on 05 VW Passat V6 (mike3366)*

Yes the right side is where the AIR pump is located...but just because you hear it running on cold start..don't jump to the conclusion that you need to replace it! Check the other stuff I told you to check..vaccum hoses in particular..much faster and cheaper than replacing the pump..which is a betch to get at...if you do need one..buy it from 1st VW parts...I bought one for my Passat..about $250-300 compared to $450-500 at my local dealer!


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