On 28/08/2025 at 07:50, Breezy_Pete said:

It has got petrol in the tank, right?

Haven't noticed an answer to this?

Ok, so the compression testers arrived, don’t need the more complicated one, used the cheaper one, identical to the one alasdair posted up further uo, I first checked it one cylinder of a Peugeot 205 petrol, registered 155 and stayed there.

So, pulled all the electrics of the injectors first so no fuel being dumped, pulled 1 of the 3 plugs again on the Fabia and put the compression tester, zero compression, tested it on the 2nd plug which I had also managed to finally get the rubber sheath from the surrounds, zero compression. I checked the battery, was resting at 12.6v and I’d charged it a few days ago, but just to be sure I gave it a boost from a powerpack.

One assumes this is now worst case scenario? It does of course crank , can see movement in the engine etc?

Are you absolutely sure there is zero compression in any of the cylinders?

Is that is the case, it is likely that the valve gear has been damaged, with all valves stuck open - although I'm a little surprised that it affected all three cylinders!

I did think it a little weird that the needle didn’t even move not even a tiny bit, that was on 2 of the three cylinders, I was thinking it might just fluff the needle but there is nothing. I will give it another shot tomorrow, it’s why I tried it on an older Peugeot engine first to make sure the compression tester functioned. I havent as yet tried the 3rd and final cylinder but if the weather leaves me alone tomorrow i’ll try that one also and come back here.

I guess swapping back from the intial odb reporting faulty cam sensor to the replacement that she got was will make an difference to the test?

Cant see the crank sensor making any difference to compression. If theres zero compression on two of the cylinders it as said sounds like a valve problem or perhaps a catastrophic head gasket failure between the two pistons or the timing chain has jumped and you have bent/damaged valves. Try the third and see how you get on plus try it again on the other car just in case the tester is faulty. Even if you have a poor seal at the sparkplug opening I would assume the needle would move slightly.

Alasdair

9 hours ago, Jogon said:

I did think it a little weird that the needle didn’t even move not even a tiny bit, that was on 2 of the three cylinders, I was thinking it might just fluff the needle but there is nothing. I will give it another shot tomorrow, it’s why I tried it on an older Peugeot engine first to make sure the compression tester functioned. I havent as yet tried the 3rd and final cylinder but if the weather leaves me alone tomorrow i’ll try that one also and come back here.

I guess swapping back from the intial odb reporting faulty cam sensor to the replacement that she got was will make an difference to the test?

Almost certain that the cam sensor fault will be caused by the cam timing going out of sync - original sensor was probably not faulty.

I'd suggest the priority would be to get a mechanic do a visual check of the valve timing.