Thread: Flashing check engine light Discovery 3S 4.0 V6

I would suggest a proper diag tool such as the IID would shed more light however Cambo above sounds like he’s on the money.

Originally Posted by DiscoJeffster

I would suggest a proper diag tool such as the IID would shed more light however Cambo above sounds like he’s on the money.

I'd love to do this, but don't have one. Is there an Adelaide member that might loan/rent one prior to me finding one to purchase?

Originally Posted by Cambo@oldjaguar

Flashing check engine light comes with excessive misfires, that's a standard thing.

My internet expert diagnosis is that the catalytic converter on that bank is choked up or collapsed.

But i've had a few cars with choked cats which caused misfires like this, so it's not a guess, it's speaking from experience.

I do like this idea, as in the absence of a manifold pressure/flow/EGR/HO2S/injector fault code then back pressure may be causing this. Also the sudden failure on a whole bank after a long drive supports this.

Given that it runs fine would I be safe driving this car?

I guess putting a pressure gauge on the upstream HO2S (O2 sensor) port might yield a high pressure if this was the error. Does anyone know if such a tool is available?

You can measure the pressure in each pipe and compare the differential pressure before and after the cat. The problem is that a collapsed or choked cat may flow enough gas at idle, but not at higher rpm under load, so how do you test under the right conditions?

In saying that, the last car I had with a collapsed cat you could actually feel the reduced flow just by putting your hand over each tailpipe with it sitting there idling.

If it is a cat issue reading the codes will show this.

If no IID tool is at hand the car needs to get to an indy or even a stealer and have them read.

Garry

Originally Posted by Julian B

Anyone in Adelaide got one and can swing by a stranded enthusiast?

The site has a list of owners of diagnostic tools. Here's a link showing Adelaide members.

Members with Diagnostic Tools

Martin

Originally Posted by garrycol

If it is a cat issue reading the codes will show this.

If no IID tool is at hand the car needs to get to an indy or even a stealer and have them read.

Garry

What's the code for a collapsed or choked catalyst?

I had a look at my PDF workshop manual.

This is a cut and paste of the P0301 code. It refers to cylinder 1. The others refer to other cylinders - P0302 to 2, P0303 to 3 etc. P0300 says "Random Misfire Detected -No sub type information"

DTC.pdf

Martin

Originally Posted by Cambo@oldjaguar

You can measure the pressure in each pipe and compare the differential pressure before and after the cat. The problem is that a collapsed or choked cat may flow enough gas at idle, but not at higher rpm under load, so how do you test under the right conditions?

In saying that, the last car I had with a collapsed cat you could actually feel the reduced flow just by putting your hand over each tailpipe with it sitting there idling.

Astute observation re conditions for testing, which I will reflect on.

Originally Posted by garrycol

If it is a cat issue reading the codes will show this.

If no IID tool is at hand the car needs to get to an indy or even a stealer and have them read.

Garry

Local independent can't see it for a month.