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7-19-12: VW MK3 2.0 ABA P0411 CODE / CHECK ENGINE LIGHT
Part 1
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I've got a 1997 VW Golf GL (MK3) with a 2.0 liter ABA engine, and the check engine light ("CEL") has been on for some time. Time for inspection in New York State has arrived, and it will not pass here with the CEL on.
Upon testing with an OBDII scanner, I found my VW is throwing the P0411 code for which this model is notorious. After reading through some forums, I found this issue is generally related to the secondary air pump, or its peripherals (hoses, EGR valve). Thus, I began my investigation there. Here is an overview - please note, the wire has already been unplugged from the secondary air pump in the picture:
Here is a close-up of the secondary air pump and its unplugged wire. As you can see, the part has a date written on it: 8-22-07. The date of this writing is 7-19-12; presumably, it has been replaced before.
When I disconnected the wire from the secondary air pump, I noticed something peculiar: there was moisture everywhere, and the connections on both the wire and the pump had started to oxidize.
. . . and another shot of the moisture and oxidization, this time showing the connector on the secondary air pump itself:
I extracted the secondary air pump by removing three easily-accessible 10mm bolts, two hoses attached with plastic clips, and the oil dipstick to allow room to take it out of the bracket. Upon removal, nearly an entire pint of dirty black water poured out of the secondary air pump!
Coincidentally, the car had been running poorly for a year after every rainfall: failing to start, requiring me to hold the key in the "on" position as the engine attempted to turn over, stalling out while idling, and failing to accelerate appropriately when given gas. I had read on other forums these symptoms were related to the ignition coil, and replaced that part two months prior. Although the new ignition coil made the car run a bit better, it didn't solve the problems.
Upon closer inspection, I saw that the hose connecting the EGR valve to the secondary air pump had a small crack in it, which broke the vacuum between the two components, and allowed moisture to enter.
I intend to purchase a used secondary air pump on eBay (about $100); the cracked hose will also have to be replaced.