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2014 Forester Diesel Auto CVT Auto
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Discussion Starter · #1 ·
In the post [Forester Fault Code - glow plug control circuit for cylinder #4] I have commented that I get the exact same problem on cylinder 4, yet my car is exactly normal when the code is reset and a reset of the one single code lasts all day at least.

Here is what I wrote on the post above (edited to add Australia and comment re Emission Control) - I will appreciate comments as I propose driving 3,600km before I can conveniently get the vehicle serviced in a large town.
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Why always Glow Plug 4?
My 2014 Forester Diesel Auto <40,000km, is currently in remote WA (Western Australia) and gets Glow plug 4 low error code. This disable cruise (flashes), shows MIL (engine) light, hill start and X-Mode flashing. Get double beep on start up, and checking Info shows Emission Control and Hill Start systems need to be checked. On reading codes, there is only a single code which translates to Glow Plug 4 circuit low.
(No codes for Emission Control ever show even tho Info reports that Emission Control needs checking)
On resetting codes, everything is back to normal and may last one or two days with only a pending glow plug code. Two or more starts early in the morning and the Pending may turn into a saved code, and bring the error back but a reset clears everything for the day and the car works perfectly normally and can clear a pending code all by itself.

On Googling the fault, found this thread. But is it more than coincidence that it is Glow Plug 4?
An off-the-cuff dealer verbal-estimate of $800-900 Aud to replace all 4 plugs and Google estimates of $120-500, makes my wonder if I should check out wiring first and find out if Glow-plug 4 problems are a built in fault. I have multimeter, but no wiring details of where to check.

I propose driving another 3,000k back to civilisation, resetting the fault code whenever necessary and checking that no other codes come up, before a scheduled service and replacing glow plug if necessary.)
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Any comments or suggestions please?
Please will someone tell me where and how to test the wiring to see if the problem is wiring or glow plug.
 

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2015 Forester 2.0 D-S CVT
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Hi Competern

I'm reading this 6 months later and hoping to learn from your experience. Three weeks ago, I started to experience the same symptoms as you did last year, except that the glow plug in question is nr. 3. Other than that, the code, the messages about emission control and hill start, the flashing and disabled cruise control and the flashing X-mode symbol are all familiar. Like you, I can delete the code and it will return again within a day.

I have been looking for a pattern without much success. It's always at vehicle start-up, never while I'm actually driving as I would expect with a regular emission control code. If I have completed a stint of highway driving for a length of time, it is less likely to appear the next time I start the car. If I drive for only a couple of kilometres or less before stopping the engine, its more likely to fail the next time.

So I'm wondering whether you learned anything from your experience that could be helpful to me?

thanks,

mhfoot51
 

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2016 2016 & 2015
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104 Posts
the main use of the glow plug is with a cold engine to ease startup so it is not illogical to trigger the error on starting the engine... the rest of the time when engine is hot glow plugs are (almost except i suppose for specific case to reduce contamination) not used so is normal not to trigger the error when engine is running.
always the same cylinder... well there has to be a fist plug dying i'm pretty sure if you carry on wating a few months/year there will be another one failing then you'll have always the issue in the same 2 cylinders...until the next one fails...
But the real problem here is to change them: due to accessibility first and second: sometimes glow plug break and the operation become immediately more expensive/complicated.
in Europe we've used diesels for ages and before the direct high pressure injection you had to wait for the preheat light to go off before startup otherwise it was a guaranteed failed atempt to start and if one was failing the startup was getting more complicated and the plugs were less solicitated (once the engine started they were off... no gas contamination consideration) so once started you had a shaky engine until hot but all ok... now you still start but the car detect the issue and let you know... saves you killing your battery.
 

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2015 Forester 2.0 D-S CVT
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Thanks for the reply, nounounounou.

As I'm in Australia, where temperatures rarely get below zero, I'm wondering if I wouldn't be better simply disconnecting the glow plugs as per advice given to Competern in post #7447577 (sorry, can't post a link, not enough credits). If the ECU objects, I could perhaps replace them electrically with an equivalent resistor / impedance. Thoughts?
 

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2016 2016 & 2015
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104 Posts
doing so you take the risque of sending unburnt particles/ashes into dpf and damaging it... no sure it is the best idea
the plugs are for helping to get in correct working temperature as fast as possible... removing them put you in bad position ... a cold start can be at 30ºC ambiant... still is a cold start... no need of freezing ice outside
 
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