Hi Everyone,

I purchased an 05 DB9 manual in February and have only put about 500 miles on it since. It was running great until I went to start it one day and it instantly went into "limp mode" Codes P2105, P2106.

I've read here that the Motorcraft coils are prone to failure causing the ECU to detect a misfire triggering the limp mode feature so as not to destroy the cats so I replaced all the coils and plugs but the faults along with the Emissions service warning Amber check engine icon and Red triangle remain (faults won't clear) and the throttle response remains limited.

I next tried a hard reset by disconnecting the battery. however the problems remained and now the window dip is inoperative. The nearest AM dealer is over an hour away and has a current waiting list of ten weeks.

Any suggestions? Does the computer need a flash/reset from the Dealer? or could I try O2 sensors? Cats? Throttle body position sensors perhaps?

Any advise is most appreciated

Regards,

drivergmx

 

You might have found this thread that sounds a bit similar: https://www.6speedonline.com/forums/...ult-codes.html

Are your throttle bodies gummed up?

Window dip should restore with reset procedure -- run window all the way down until it clicks, all the way up until it clicks.

 

Hello yvr,

Thank you for your prompt response. Yes when I had the intake manifolds off to facilitate the spark plug and coil replacement I thoroughly cleaned and inspected the throttle bodies. The plates move through their full motion without binding and spring back to the fully closed position. Mechanically they seem fine but I have no way of testing them electrically unless I could find the resistance values and check them with a meter.

The window reset procedure seems simple enough. Thank you for that. I think what I'll do is leave the negative battery lead off overnight and try it again. If the lights extinguish and the throttle response is restored I will perform the window reset and attempt a misfire correction/coast down (x4).

If that doesn't do it I may have to suck it up and tow it into the dealer like a helpless fool. I am an aircraft mechanic who prefers to do all my own repairs whenever possible. To me, having to rely on a dealer is a fate worse than death. I'd rather fly to London and sit through the three week factory AM tech certification course at my own expense than pay a dealer if I had the time (which I don't)... But short of just continuing to throw parts at this. I may have to.

 

if fault at start of your journey was misfire due to plugs or coils, the DTC would start with P0300 for random / general misfire then a number counting up from 301 to identify a specific cylinder.

before you submit to 3 weeks of bad weather and worse food, throw a throttle pedal at it. Because without delving further into the reasons for the codes you have, pedal would be first / obvious guess

 

Good Day Mr Rose,

I think you are onto something here. Some of the faults that cleared prior to the plugs and coils being replaced were:

P2106 Throttle Actuator Control System - Forced Limited Power
P0109 Fuel Rail Pressure A Circuit Range / Performance
P2105 Throttle Actuator Control System - Forced Engine Shutdown
P2138 Throttle / Pedal Position Sensor / Switch "D" / "E" Voltage Correlation

Since the vehicle had 50,000 miles at the time of purchase and no record of the Plugs and coils being replaced I took it on myself to start there just to bring the service up to date. But the codes do point to a throttle actuator control issue. I thought that since these messages cleared they may have been caused by a misfire but since no P0300 codes were present perhaps a Throttle Position Sensor is at fault.

I'll see if one can be purchased locally and let you know.

Regards,

Glenn

 

Following up I reconnected the Negative battery cable and successfully performed the window dip reset procedure. Thank you yvr, Next I started the engine and the faults remained (limited throttle response). So going on the information provided by MR. Rose:

I disconnected the intake plenums at the Throttle Body inlets on both sides and using a mirror, I placed the key in the on position and depressed the accelerator pedal. This visually confirmed that the right side Throttle Body was operational but the left side was not.

Next I swapped the left Throttle body into the right position and confirmed it was also operational.

I next checked fuses F4 PCM A and F5 PCM B which checked normal.

So I went to the Accelerator Pedal and tapped it with a wooden handle to see if I could get the left side working and then suddenly both sides stopped working. If that isn't a hard Fault confirmation then I don't know what is...

So I've put in a parts request with Alistair at Astonmartinbits.com for a 6G33-9F836-AC Pedal Assy, Accelerator.

Thanks again for your assistance,

Glenn

 

So, In conclusion I managed to find a good used accelerator pedal with 8,000 miles on it on ebay from a dismantled Vantage in California and had shipped. Once installed I cleared the faults and took it out on the highway and performed the misfire correction. No further faults present and operation is normal (awesome).

Thank you once again for you assistance

 

Glad to hear you're not limping anymore Good result.