Cold Start Issues

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Azmuf1

New Member
Joined
Jul 6, 2022
Messages
10
Location
Leamington
Car
Mercedes Cla
Hi guys,

I have an issue with my 2014 2.1 cla diesel.
Since the weather has become slightly colder, the car takes a lot longer to start up first thing in the morning. (After that it is fine)
Two days ago after the car was not driven for a few days it never started until the 2nd time of trying & the engine management light came on but went off and has not come back on after switching the car off. I ran a scan on the i car soft but found no codes.
I find it only happens on cold mornings.
Any ideas what it could be ?
Thanks
 
Hi guys,

I have an issue with my 2014 2.1 cla diesel.
Since the weather has become slightly colder, the car takes a lot longer to start up first thing in the morning. (After that it is fine)
Two days ago after the car was not driven for a few days it never started until the 2nd time of trying & the engine management light came on but went off and has not come back on after switching the car off. I ran a scan on the i car soft but found no codes.
I find it only happens on cold mornings.
Any ideas what it could be ?
Thanks
Glow plugs, glow plug relay, battery failing or any combination of these would be the likely reason.
 
Thanks
I got the battery checked this morning and was 11.4 volts. The lad said it was fine and to take it for a long run.
If it is the glow plugs on controller how can i confirm this as no codes have came up on the icar scan.
 
Thanks
I got the battery checked this morning and was 11.4 volts. The lad said it was fine and to take it for a long run.
If it is the glow plugs on controller how can i confirm this as no codes have came up on the icar scan.
11.4 V is far from fine. A healthy fully charged battery should be around 12.6V Are you sure he didn't say 12.4V?

Did the "lad" check the alternator output? That should give around 14.2 to 14.6 V with the engine running

Glow plug faults often don't set a code. You could measure the voltage at each glow plug or check each plugs resistance value but I would start with someone else checking the battery under load and charging system.
 

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No idea about the CLA in particular but a failed plug will typically cause the glowplug light to come back on after starting, and stay on for a minute or two. You can see in STAR which plug has failed. Failed relay/control module may not show anything (on our Vito the glowplug light would come on randomly for a few minutes while driving). There's also a separate 'mega fuse' for the glowplug circuit (225A in our Vito!).

But as mentioned the battery should be way above 11.4V ... for a wet lead/acid battery 11.9V is fully discharged, and for an AGM one 11.5V is around 10% charge remaining.
 
do you have any kind of code reader capable of live data? Check rail pressure during long crank, when it jumps up, and how high...
yes, faulty glow plugs may cause staring problems too
 
Thank you for your responses
Update is car has been starting fine so far but took a little longer to start up but started on first attempt
I checked the battery again this morning and was 11.9v before starting.
With the engine running it went to 14.7v
I have tested the battery to make sure nothing is draining the battery when switched off & that is all fine.
Will keep an eye on it but seems like weak battery unless i am wrong.
 
Yup if the battery is getting 14.7V with the engine running it should charge. Maybe check the resting voltage 30 mins or so after a run to see what it shows then.
 

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