Restarting your Engine for the First Time after Changing the Spark Plugs and Coil Packs in an Aston Martin DB9

The moment of truth is fast approaching.  You’ve just spent a considerable amount of time tearing your beloved DB9’s engine apart to change the Spark Plugs and Coil Packs, presumably like me to cure an issue with a Lumpy Idle.   If you’ve been following my procedures laid out in this blog, you are on Step 20 sumth’in of many.   Hopefully your workbench is devoid of left over nuts or bolts.  All that’s left is firing her up to see if your work has been successful.  There is a process to this and the few remaining steps. Continue reading “Restarting your Engine for the First Time after Changing the Spark Plugs and Coil Packs in an Aston Martin DB9”

Depressurizing the Fuel System on an Aston Martin DB9

Aston Martin DB9 Fuel Charging SystemYou may need to depressurize the fuel system on your DB9 if you are going to do any work with the fuel rails or fuel injectors under the hood.  I am doing this as part of changing my coil packs and spark plugs, but you might be wanting to change a fuel injector or various other engine service tasks.  Normally the fuel system has ~40psi of fuel pressure (even when turned off as residual pressure), and if you are going to disconnect something with the fuel system under the hood (bonnet), you don’t want the risk of it spraying you, your car, or worst of all causing a fire.

Depressurizing it is fairly simple.  We are going to run the engine out of gas by removing a relay that operates the fuel pumps.  No fuel = no pressure.  Easy. Continue reading “Depressurizing the Fuel System on an Aston Martin DB9”

OBDII P Codes on an Aston Martin DB9

P Codes found on an Aston Martin DB9
P Codes found by OBDII reader

While servicing your DB9 you might run into a situation where your dash display or OBDII reader shows you an error message in the form of a cryptic P code like P1488, setting the stage for an ominous visit to your local dealer and the commensurate drain on your bank account.  Without any reference, your tendency might be to stick your head in the sand and just drive on risking damage to the car.  In this post I wanted to publish a list of all the P codes I could find so that it might help steer you in the right direction to taking care of the issue yourself.

Some P codes are innocuous.   For example, P1488 [Exhaust (muffler) Bypass Control Circuit] is logged if you pull the famous Fuse 22 to uncork your exhaust.   The car knows Fuse 22 is pulled, makes a note of it, but doesn’t set off the idiot light (Malfunction Indicator Lamp or MIL).   If you find this code and you have pulled your fuse, you can just ignore it.

Aston Martin Diagnostic Manual

Aston Martin OBDII Diagnostic Manual - Preliminary Issue Cover
Download the Aston Martin OBDII Diagnostic Manual – Preliminary Issue

I have gathered the list below from a preliminary publication of the Aston Martin Factory “OBD II Diagnostic Manual” published in April 2004.   The publication is a great resource, and has a tremendous amount of detail about each P Code, and other theory about the cars operation and diagnostics.  356 pages of technical details and some very helpful diagrams.   Being that it was a preliminary publication it’s a good starting point for the early cars (MY 04/05/06), but I am certain that as the DB9 was developed more codes were added and this list is incomplete.   The official place to get the P codes explained is on the Aston Martin Technical Information Website (which I have covered in another blog post).   What I dislike about the format on the website is that the codes aren’t in a single document anymore, but rather each has its own web page section.  This makes a lot of sense for Aston Martin (alleviates the need to keep a large complicated document up to date), but for us DIY repair guys without an expensive $2,600 annual subscription to the website it’s a handicap.   So, I would recommend that if you find the P code you are experiencing in the list below just check out the PDF.   If the P code you have isn’t listed, perhaps spend the $100 for a one day subscription to the website and look up the code you have (and maybe send me the details or your code and a PDF print of what was on the website about it).  Or succumb, and take your car into the dealership. Continue reading “OBDII P Codes on an Aston Martin DB9”

Using an OBDII Code Reader with an Aston Martin DB9

Using an OBDII Code Reader with an Aston Martin DB9If you are brave (or dumb) enough to do some of your own maintenance on your Aston Martin DB9 one great tool to have in your repertoire is an OBDII code reader.  OBDII stands for On Board Diagnostics version II – an industry standard communication method that modern cars with computers use.   By linking up your OBDII reader to the car, you can ‘talk’ to it, learning some real-time information from the cars Powertrain Control Modules (PCMs).

Aston Martin Check Engine Light
Dreaded Check Engine Light (CEL)

Of particular use is to understand what’s going on if the dreaded Check Engine Light (CEL) comes on.  This is also sometimes known as the Malfunction Indicator Light (MIL) or Idiot light.  Without a code reader you are completely in the dark as what might have tripped the CEL, and at the mercy of a Dealer to find out what’s going on.  With a code reader, you can link up to the car and it will tell you a much more specific error code (a P code in Aston Martin speak).   This will narrow down your troubleshooting greatly, and often it can be a simpler DIY issue to address and then clear the error code and reset the CEL. Continue reading “Using an OBDII Code Reader with an Aston Martin DB9”