Crankshaft sensor fault
 

Ok so I bought a 2001 V70 T5 with a starting fault
Had a play and it seemed to be fixed although took slightly to long to start
Got an mot so happy days I thought
After a short time of using it I noticed it getting longer to start, then a lot longer followed by sometimes it going into limp mode and also locking up sometimes while cranking, almost like a hydro lock but only for a plot second
Had it on the diagnostics at a local garage and it was showing an engine speed sensor fault.
The mechanic said it'll be a crank sensor, and that all the symptoms suggested a crank sensor issue
I had a search on here and felt confident that the issue seemed to be the same as a few I'd read and a crank sensor would fix it.
So.... Bought a new one, fitted tonight, no difference at all,
Ant thoughts???
Thanks in advance

Sounds more like a starter motor related fault. Either the motor or solenoid or wiring.

Based on the described symptoms, your mechanic's crank sensor diagnosis was a joke unfortunately.

Not starter as sometimes it'll crank for maybe 20 seconds before it starts but turns over quickly enough.
I was with him when he had his Snapon diagnostic kit connected, definitely said engine speed sensor as the only fault showing, he cleared the code and the car started ok, although sometimes it does anyway

A sensor fault code doesn't mean a sensor fault though which is kind of page 1 of code reading.
He can use live data to view the engine cranking speed and fuel pressure and several methods to verify a spark.
He can also test the "faulty" crank sensor with a multimeter.
There's no description of any of that being done.

For an engine to run, you need air fuel, compression and a spark and testing all 4 should be bread and butter to a mechanic.

In his defence I was there dropping my brother off to collect his car and asked if he'd mind quickly reading the codes for me to give me a starting point to look at.
I just wondered if anyone else had found the same fault or if an engine speed sensor fault could mean cam sensor instead of crank perhaps??

You described some kind of stopping of cranking like a hydro lock. That's nothing to do with a crank sensor so my view of the mechanic is the same.

Did he clear the fault and it returned?

The wiring to the sensor could be faulty for example.

It hadn't don't the lock up think at the time of getting it diagnosed. That's only started this week since I've had the sensor in order
I did wonder about the wiring. Is it easy to check?
He did clear the code and yes the fault has returned

It's easier to start with live data for the cranking speed.
If the engine is turning fine but the data shows no or low rpm, there's a signal fault.
If the data shows a healthy rpm in line with what you can hear, you need to look elsewhere.

Cheap diagnostics like an ELM327 will do fine.

I'll have a word with a mate who's a mobile mechanic, He has a generic diagnostic that has live data. It's the lock up that confused me. I thought that could only happen if the timings out but once started it runs great

Presumably, it's been confirmed you're getting healthy sparks at each of the plugs? I've read that you'd struggle to better genuine Volvo plugs so that might be something to consider if the current ones are old or aftermarket.