Hi all, I am a new member just having purchased an 07 GTC in November in San Francisco. Being that I live in Sacramento, over a 100 miles from the nearest dealership, and am somewhat mechanically inclined, I am hoping you guys can steer me in the right direction. I had my car checked out before purchase at the dealership, and everything was ok. A couple days ago, my check engine light came on solid, and started blinking at idle. The car was idling rough so I immediately parked it. My OBD code reader gave me 10 codes 0300, 0307-0312 (which basically say cylinders 7-12 are misfiring) 1411 (secondary air injection sys bank 2 flow too flow) 2587 (short in pass seat detection) and 3084 (could not find). Thanks in advance for any ideas, suggestions or recommendations.

 

How many miles on your car? Any strange smells? There are a host of problems that can activate the CEL. e.g. ignition coils, plugs, vacuum leak, bad cat, etc. The DTCs you found suggest the misfires are all on the 2nd bank (driver's side on lhd vehicles). Check the connection to the engine management ecu's (passenger side on lhd vehicles near the firewall in the well). Look for any trapped water or moisture in the well. There is a drain hole that gets plugged. There are posts on this forum that discuss this issue.

 

Thanks for the response. The car has 26K miles, and I have not noticed any strange smells. I just took it around the block, and although the solid engine light is still on, it did not start blinking or run rough at idle. I spoke to a dealer, and they are going to have it towed in to perform the coil pack replacement campaign, and take a look at it. I checked the passenger footwell for moisture, and there was none whatsoever. I am tempted to drive it if the problem does not reappear, but am a little nervous and unfamiliar with this vehicle.

 

Once the light is triggered, the engine must be recycled "n" times before it will clear itself and only if there is no remaining fault. I'm not even sure it will go out unless you first delete the dtcs with your computer. If you erase the dtc, you will probably have to drive the car about 21 miles to ensure the actual error has been eliminated.

While checking the passenger footwell is a good idea, I am actually referring to the engine side of the firewall. If you lift up the cowling cover by the wiper arms on the passenger side, you will see a cavity. Shine a flashlight down there and look for moisture. That is also where to check the connections to the engine management ecus.

From the sounds of it, you are sending the car in for further diagnostics. I knew about the early (i.e. 04-05) cars being eligible for an ignition coil pack upgrade, but didn't realize that covered 07's. I was told by the factory that they had solved the weak coil problem prior to that. I am curious to learn what the dealer discovers.

 

Mark at Los Gatos Luxury cars told me the coil packs and labor would be covered. He recommended replacing the plugs which makes perfect sense, but said I should keep the OE plugs. The DIY info George sent me (Thanks again Geo) suggested switching to NGK iridium. I don't know if I should ignore the service techs advice on OE, though. I read in a thread that I would need a Bentley wiper removal tool to look in that tray, is that right?

 

If we can believe your computer, it seems unlikely all six coil packs on one bank would suddenly go at the same time. It still feels to me like an ecu and/or connection. Still, it would be foolish not to accept an offer for free ignition coils. Changing them is a fairly big deal as the plenum has to be removed.

There are two cowls under the hood by the firewall. One is slotted (immediately under the wipers) and the second is ventilated with holes and is closer to the engine itself. You will see the washer filler cap. The 2nd plastic cowl cover is held down (on my 05) by twist fasteners. You don't need to remove the entire plastic cover, just lift up one side and look underneath. No special tool is required. I used OEM (NGK 101905600B PZFR6Q-11) plugs on my car with excellent results. Your plugs should be good for at least 40K miles.

 

I was able to loosen the cover and look without actually removing it, and it was dry. The connections that I could see looked OK. I ran quite a few errands close to home today, and everything seems fine now. Do you think a loose oil cap might cause the engine to misfire like that? I agree that I should definitely get the coils replaced, and am waffling on the plugs. At my current rate of driving, it might take me 2 years to get to 40K. Thanks for all your help!

 

It's pretty difficult to remotely diagnose the CEL. I know a loose gas cap can trigger the light so, maybe a loose oil filler cap can also trip it. When you say, "everything is OK now", do you mean the light is off and you have driven more than 25 miles without it coming back on? If you are going to get the coil packs replaced, it makes sense to do the plugs at the same time. While the plugs are relatively expensive, the labour and the coil packs are the big cost.

 

You might want to do an engine smoke test, as the 07 GTC here had the same symptoms and we know there is a defect in the air lines of this series. Hope yours is not the same as repair costs are well over 4k due to needing the engine out to repair.

 

The rough idle has gone away, and the car seems to be running fine. I have probably started and stopped it over 20 times, and driven about 200 miles over the course of a few days, and no issues. I am going to take it to the dealer and have them to check it out more thoroughly. Steven, do you know if the air line defect was covered under any recall campaigns or TSBs?

 

Is the CEL on or off at this point?

 

It's still on. My oil service interval came up right before this all happened. I know it's not related, but I'm changing the oil right now. Pretty straightforward with the help of the kind folks on this forum (and plenty of Mobil1 0w-40).

 

Can you turn the light off with your computer? If so, clear all DTCs. The CEL should be off. If not, disconnecting both batteries (right side [looking at the car from the rear] and then, the left side will clear the CEL. Leave disconnected for 30 seconds and then reconnect in the reverse order (i.e. left and then right). The car will need a few minutes to sort itself out, but the CEL should be off. At this point, you should take the car for a 20 mile (circa) trip and see if the CEL light comes back on.

 

Alas, no official recall that i am aware of and after speaking with one of the top officials at Bentley USA due to this seemingly known defect. When the 07 GTC was in for this situation, Bentley made no effort to assist with it financially nor take any responsibility "due to the car's age" even though it only had a mere 28k miles or thereabouts on the odometer. As this was the second B within my stable you'd also think that as a loyal driver........

 

Finally got the car into the dealership. Vacuum test reveals that the fault code is a result of the dreaded "engine out" vacuum leak. $8900 to fix! I wonder how much Jiffy Lube would charge? I guess I'll get some estimates from Indys in the area...