Electrical How To fix P2300 and P2303 codes

valvashon — Tue, 05 May 2026 21:09:14 GMT

If your car (any first generation MINI) is stalling unexpectedly and throwing P2300 and P2303 codes (coil circuit A and B low) here's how to fix one of the causes, even if it's just one of the codes. In my case (2003 R50) I replaced the plug wires, the plugs and the coil (twice!) and it was still stalling at the worst possible times, such as when I wanted to leave work and also in heavy street traffic. Clearing the codes would get it to start again but that is not a proper fix. Since I had replaced all the "discrete" parts I turned to the wiring harness. At first I was going to jumper the hot lead from the coil right to the battery but then I discovered by accident that moving around the wires that were in the three pin connector at the back of the coil would make the car stall out on a consistent basis along with always throwing those two codes. This meant that the problem was bad wiring, but was there a fix other than a whole new wiring harness under the hood? There was! Here's the relatively simple fix with lots of pictures. You will need the new connector, a soldering station and the knowledge of how to use one, heat shrink tubing of the appropriate size and a heat gun:

Here's what I had to do so I could get to work the day after the discovery before I could get to the auto parts store. Two zip ties to keep the wires from moving around and opening the (presumably) red/hot wire to the coil.

Here's the new end I purchased. It's a relatively common automotive connector. This was a "Standard" brand S738 wire/connector assembly. I purchased mine at O'Reilly Auto Parts, I'm sure they have it or an equivalent at many auto parts stores.

Bad, bad end pulled off of the coil. You have to push the red thing off to the side before it will unclip.

Old at the top, new at the bottom. As you can see the new one will fit.

Pull back the protective heat sleeve and hold it back with a large binder clip. Ignore the black tape, it's over where I stripped some insulation away to be able to measure the incoming voltage. Problem started long before I stripped that wire.

Scrunch that protective sleeve all the way up to the end that goes into the fuel rail.

I cut the old connector off with about 5 inches of wire left on the old connector. Cut about an inch off of the wires on the new connector and the length will be about perfect.

Strip the ends of each wire and twist them together as shown wrapping them together. I'll include the color to color code below since they are not the same.

Here's what your soldered together wires should look like. These should have been twisted together a little better but they will hold. I had to sandpaper the end of the wires on the car to shine them up a little for proper soldering. Use rosin core flux solder, not the kind for plumbing.

Slide the shrink wrap around the splice and heat.

Her

Here's all three wires ready to go!

here

Here's the heat shield covering pulled back down the wire harness. I could have left another half inch to an inch of wire on either end but this actually fits quite well.

Here's the new connector in place. The red thing pushes over when the connector is fully seated and you want to have that over and holding it all together. It took a lot of fiddling and pushing to get the new connector fully seated but this connection is rock solid, just like you want it to be. Taking the coil off of the valve cover may have made the connection part easier. Wiggling the wires while it's running now does not make the car stall out!

For the Standard S738 the wires go:

[car] to [new harness]

red to black
black/yellow stripe to orange
black/blue stripe to brown

If you get a different brand of this connector your wires may be different. Make sure you wire it properly! And don't use those butt splices, learn to solder or find somebody who can. You don't want to put anything mission critical through those things.
This whole fix took me less than an hour.
If this helps you fix your car let me know in the comments.

Thanks!

Val

North American Motoring - How to

Electrical How To fix P2300 and P2303 codes