The other week I got the enginer management light come on. (mentioned earlierin another post but just a dead end really)  So, I bought a cable and software and the fault was .. exactly..

 

Stored DTC(S)

P0684 - Glow Plug Control Module to PCM Commmunication Circuit Range/Performance

 

I found a great webiste here ... https://www.obd-codes.com/p0684 which pretty much covered everything ... apart from where all the respective componants live??

 

Anyway ... I reset the code but seeing as the ambient temperature is great today I'm not really surprised the fault hasn't returned.   It's got a its service due in a few months and so I'd really like to sort this myself before then.

 

Could someone help with the locations of the GPCM, PCM and the solenoid.

 

If the fault was with a glow plug wouldn't I get some other code indicating which one had failed?

 

Thanks

FWIW I recently replaced all 4 glow plugs on an Astra CDTi 1.9 with only 50,000 km on it. Every one of them was dead. You can check glowplugs are working if they measure < 1 ohm resistance, or remove them and check they glow with 12V from the battery applied. 

 

 

Anyhow, when I read around online these things are supposed to last 150K KM, but after my experience, that's not likely

Thanks for the info. There are numerous bits online about checking the glowplugs.  Mine appear to have 3 wires to them?  also the connectors are very tight ... I'm not too happy about renching them off in case I damage anything.

 

So,  I'm still trying to find the whereabouts of the componants?

 

Thanks

 

 

I've done a bit of exploring of the engine and I thinki I've found the glow plug leads.

 

Could someone please have a quick look at this video just to confirm that what I'm looking at are indeed the glow plugs?  Also, why does one of the leads (second one in from the right) look different (wider), to the others? - and you can see 3 wires going to it???

 

I've tried coaxing the leads off off the plug but they are really firmly attached.  If I'm to change these plugs I'm going to have to use some plyers or dismantle some parts to get a decent grip.

 

Thanks

This way ...

 

 

Here's a good tool for the job

 

https://www.ebay.com.au/itm/3-pc-piece-Long-Reach-Hose-Grip-Pliers-33-New/191920707405

 

 Long Reach Hose Clamp Pliers

Edited 25 May, 20206 yr by digifish

Hi all, my 'check engine' light came on this morning with no errors. I dug out an old ODBII Bluetooth adapter and read the code as follows -

 

P0684 [0x0684]
Glow plug control module to ECM/PCM communication error - range/performance problem
Status: Confirmed

 

04976 [0x001370]
P068400: Glow Plug Control Module to PCM Comm.Circuit Range/Performance
Status bits: 1
Priority: 2
Frequency: 1
Unlearning index: 255
Odometer: 213718 km
Date, time: 2024.09.24 06:59:43
Engine RPM: 804 rpm
Calculated engine load value: 88.63 %
Vehicle speed: 0 mph
Engine coolant temperature: 14 ℃
Engine oil temperature: 14 ℃
Barometric pressure: 14.358736062693 psi
Klemme 30 voltage: 11
Paramteric values:  20 96 28 13 BB 82 94 11 89 00 11 1F 00 11 12 BD 00 B0 16 44 02 EE 16 45 00 EF 16 25 0B 2D
Status: Test failed, Test failed (current drive cycle), Pending, Confirmed, Test failed since last DTC clear, Warning indicator requested

I'm really not confident with an engine or checking currents and such, but reading the first post, I wonder if I should just reset everything and see if the error comes back?

 

Thanks for any advice anyone can offer.

 

Hi. I had this problem and it was the control module which needed replacing - the glow plugs were fine.

I could reset but the light kept coming on and I had some intermittent starting issues.

Super straightforward - the control module was approx. £100 from my local Skoda dealer although the non-Skoda Bosch module is much cheaper.

Part number: 04L 907 282 B

See this thread: 

 

Edited 26 September, 20241 yr by Jonny_C