W169 A Class refusing to start after completing a journey

[Abb]

A bit of an odd one me thinks, this one. My father contacts me today stating he has broken down having pulled over to take a call. He had been out in his 2008 W169 A150 petrol (mileage circa 36k), went to start the car and nothing! Lights on the dash illuminate but engine doesn't turn over let alone fire.
Long story short, manages to get the spare key, tries that and hey presto car starts straight away and off he goes home. I turn up change the batteries in both keys (1 which had never been used), plug my icarsoft scanner in and no fault codes found.
Tried both keys and the car starts as per.

He pops out later and same thing happens. Lets the car cool down and the car starts up fine again.

The car battery is fairly new, the car itself is pristine and very well maintained and has proven faultless in the years he has owned it. Before getting it down to the indie to get it on star to see if that shows any codes logged, could this be the crankshaft position sensor? Its has shown no other symptoms and no EML warning lights either to indicate a fault.

 

[clk320x]

The fact it starts when cooled down suggests CPS ?

Good luck pal.

 

[wongl]

If the lights come on but the engine doesn't turn only while hot, I would suggest starting the fault-finding around the starter/relay.

Need to verify - when the engine fails to turn-over, is this failure consistent with both keys?

 

[Major774]

Sounds like a failing CPS.

 

[Deleted member 149005]

Sounds like a failing CPS.

we have a second place

 

[Abb]

Thank you for the replies. A little update, the fault is not consistent with the engine cooling down.
have driven it today, stop start, no issues at all!
What I have since found out, when it did fail to start, there was a very faint ‘click’ sound, almost what would appear to the same noise a solenoid/relay would make.
Am I delusional, or would there be one fitted somewhere, and this failing which would cause this issue?

 

[GLK]

I've had very similar, if not exact symptoms (only for a couple of days - booked it to a trusted indie right away), got a starter motor replaced - all sorted.
That was exactly three years ago ...

 

[markjay]

If you can hear the solenoid clicking but the starter motor isn't turning, then the issue is either a faulty battery, or a faulty starter/solenoid. Generally it's an easy fix, but it will depend on how accessible the starter motor is - from memory the engine configuration on the original A-Class is a bit odd.

 

[Abb]

Thanks again. It’s definitely not the battery and it’s been booked in to the indie next week.
Will price up the starter.

 

[clk320x]

Thanks again. It’s definitely not the battery and it’s been booked in to the indie next week.
Will price up the starter.

If I remember correctly the labour is about 2x the cost of the OEM part. David @GLK can confirm

 

[GLK]

If I remember correctly the labour is about 2x the cost of the OEM part. David @GLK can confirm

Yes, it was ... it's quite a job to get to it, so fair enough.

 

[clk320x]

Yes, it was ... it's quite a job to get to it, so fair enough.

Do you remember how many hours it was David?

 

[Benzowner]

Seems strange its only when hot, from experience the CPS will let you down whenever its inconvenient Is there a thermocouple on these cars? A friend of mine had similar problems on his car, not Mercedes, and it was a control unit which had a thermocouple in, got hot and shut down starting.

 

[GLK]

Do you remember how many hours it was David?

I'm afraid not ... either three or four I think, but don't quote me on that ... could be less?
I know, I thought Harrow was pretty errr ... uninspiring, as I had to kill a few hours walking around, waiting for Terry to do his magic
Perhaps it wasn't as long as I felt

 

[amelbeach]

Not rolling over being a sales feature

 

[MrGreedy]

I've bought an alternator from Merc before. I think it was about £200 once I'd returned the old one for a rebate. (not including fitting). I thought at that price and because I wasn't fitting it, it wasn't worth faffing trying to.find a cheaper OEM one, only to find out it was the wrong one for some reason and blow any savings on additional labour

 

[MrGreedy]

Oh, and to add:

When my CPS went (crank position sensor), it would crank fine but not start. But some time later it would.

When I had starter motor issues, it wouldn't crank. By no means definitive, but the CPS needs the flywheel moving to do it's checks was my understanding, so I would guess CPS issues might be less likely to be a cause of no cranking? Just a guess.

 

[Abb]

Thanks for all your help folks. Hopefully indie will get to the bottom of it. Hasn't let him down since the last time I mentioned it, typical intermittent fault

My money is now on the starter motor solenoid/relay, if it needs to be replaced, have been informed it is a swine of a job to do as the front subframe needs to be dropped

 

[amelbeach]

A bit of an odd one me thinks, this one. My father contacts me today stating he has broken down having pulled over to take a call. He had been out in his 2008 W169 A150 petrol (mileage circa 36k), went to start the car and nothing! Lights on the dash illuminate but engine doesn't turn over let alone fire.
Long story short, manages to get the spare key, tries that and hey presto car starts straight away and off he goes home. I turn up change the batteries in both keys (1 which had never been used), plug my icarsoft scanner in and no fault codes found.
Tried both keys and the car starts as per.

He pops out later and same thing happens. Lets the car cool down and the car starts up fine again.

The car battery is fairly new, the car itself is pristine and very well maintained and has proven faultless in the years he Showbox jiofi.local.html tplinklogin has owned it. Before getting it down to the indie to get it on star to see if that shows any codes logged, could this be the crankshaft position sensor? Its has shown no other symptoms and no EML warning lights either to indicate a fault.

Not rolling over being a sales feature

can this be right ?

 

[wongl]

Oh, and to add:

When my CPS went (crank position sensor), it would crank fine but not start. But some time later it would.

When I had starter motor issues, it wouldn't crank. By no means definitive, but the CPS needs the flywheel moving to do it's checks was my understanding, so I would guess CPS issues might be less likely to be a cause of no cranking? Just a guess.

See post #3 above - if the engine doesn't crank it is likely to be starter motor, relay or key issue. But since the dash lights come on but not cranking, likely to be starter motor related. The CPS only comes into play when the engine is turning over.