Technical Random (flickering) Check engine light

[ZaphodB]

Hi folks, had a weird one today (and a few days ago)

Out of the blue the check engine light will flicker and 'check engine' will also randomly flicker on......

It was (is) hot today 28 degrees , and I seem to recall the other day it happened it was hot.....

Today I was waiting in traffic when it first started, (it was only a short drive to the post delivery depot), appeared to clear as traffic got moving again, no loss of performance to speak about.

Then 1/2 a mile later I'm stuck at a red light for30-45 seconds or so behind a car, and it came up again , just as the lights were changing !! , he moved off and the engine stopped just as I was about to clutch and engage 1st !!!...

Restarted ok, and I drove a further 1/2 mile to my destination without a problem....

and it was AOK as I went back to work (about 4 miles)

A bit puzzling .... I was thinking it's extreme heat and sitting there idling , where something just goes over a temperature threshold....


I read somewhere if it's flickering it's ignition related/coil pack/spark plug ? or maybe it's a crank sensor ?

Nothing shows up on MultiECU as a stored fault, which is frustrating....

Any pointers?

 

[bugsymike]

Hi folks, had a weird one today (and a few days ago)

Out of the blue the check engine light will flicker and 'check engine' will also randomly flicker on......

It was (is) hot today 28 degrees , and I seem to recall the other day it happened it was hot.....

Today I was waiting in traffic when it first started, (it was only a short drive to the post delivery depot), appeared to clear as traffic got moving again, no loss of performance to speak about.

Then 1/2 a mile later I'm stuck at a red light for30-45 seconds or so behind a car, and it came up again , just as the lights were changing !! , he moved off and the engine stopped just as I was about to clutch and engage 1st !!!...

Restarted ok, and I drove a further 1/2 mile to my destination without a problem....

and it was AOK as I went back to work (about 4 miles)

A bit puzzling .... I was thinking it's extreme heat and sitting there idling , where something just goes over a temperature threshold....


I read somewhere if it's flickering it's ignition related/coil pack/spark plug ? or maybe it's a crank sensor ?

Nothing shows up on MultiECU as a stored fault, which is frustrating....

Any pointers?

Nothing coming up as "intermittent" on your diagnostics?
For it to die, as you suspect certainly worth checking ignition side,.
Do you think next time you can see if rev counter stops instantly suggesting crank sensor, especially as heat related.
Other than that, a dry connection?
Always annoying when issue not happening when you want to test it.

 

[ZaphodB]

Because it eventually cut out earlier today, I don't believe it's a coil pack (because surely it would just run a a bit rough )

I'm thinking crank sensor, because that surely would cause complete engine stop ... I've just had it on MultiECUScan whilst idling and it eventually (after engine had warmed up to normal temps) flashed the 'check engine' and flashed he engine light at the same time a few times.

But it never stopped this time, I was monitoring various things on MES and nothing stood out .....

Maybe MES can't see basic obd codes?, it's a bit unclear to be honest which ECU to choose (but I've worked out I don't use the yellow adaptor when interrogating the ECU (but yellow adaptor is used for every other module)

I'm surprised it's not logging a fault to be honest , I might speak to MES tomorrow just to make sure I'm right in not using the yellow adaptor for talking specifically to the engine ECU

 

[bugsymike]

Because it eventually cut out earlier today, I don't believe it's a coil pack (because surely it would just run a a bit rough )

I'm thinking crank sensor, because that surely would cause complete engine stop ... I've just had it on MultiECUScan whilst idling and it eventually (after engine had warmed up to normal temps) flashed the 'check engine' and flashed he engine light at the same time a few times.

But it never stopped this time, I was monitoring various things on MES and nothing stood out .....

Maybe MES can't see basic obd codes?, it's a bit unclear to be honest which ECU to choose (but I've worked out I don't use the yellow adaptor when interrogating the ECU (but yellow adaptor is used for every other module)

I'm surprised it's not logging a fault to be honest , I might speak to MES tomorrow just to make sure I'm right in not using the yellow adaptor for talking specifically to the engine ECU

Sorry I can't advise on MES as I use MaxiEcu scan tool or my mates Snap On Zeus professional one.
I would have thought MES would have no problem doing basic OBD stuff as well as Fiat Specific, I know my MaxiEcu does.
The Crank sensor failures I have been involved with were usually with a warm engine and would die completely, cool down for ten minutes then happily start up as though nothing wrong, but I have heard others say different.
Apart from running the engine and touching various wiring connectors etc. to see if you can encourage a breakdown.

 

[ZaphodB]

I've ordered a crank sensor first on a whim.... and the fact that a genuine brand new Bosch is only £18 currently delivered.

We'll see if that helps , I'll report back