Hello I own an Audi A4 2008 2.0ltr tdi CAGA engine code in winter the car is difficult to start (Summer it’s fine ) I replaced the battery , glow plugs and relay still difficult to start I have yet to test the voltage to the plugs the fuses in the boot above the battery are fine any thoughts would be gratefully acceptable .Derek

Following this as I have the same problem with mine, I’ve just got a battery charger & that’s helping getting it started through the winter x 

Hello both,

I depends what you mean by difficult to start.

If you mean the engine turns over slowly, then check battery (may test OK at normal temps., but can suffer from voltage drop at low temps.), battery terminal connections, main body and engine earth connections, starter motor issues and connections on to this. 

Its worth noting that Diesel engines run at over twice the compression ratio of petrol engines, so all the above are under greater stress than petrol engines - particularly at low temps., and batteries will need to be heavier duty to cope with this. 

If the engine turns over enthusiastically at low temperatures, but the car is still difficult to start - refer back. 

Kind regards,

Gareth. 

Hello both,

I’ve had already had a couple of PMs from Charlotte giving more detailed,meaningful information against other issues with this car. I’ve replied to her and thanked her for that.

I’ve now had a PM from Derek - the original poster on this thread. This PM gives some - generally already known information, but nothing in reply to clarifying the ‘slow to start’ question:- engine turning over slowly, or enthusiastically but slow to start/fire? 

I wonder if I can ask posters not to PM me with answers to questions asked in the open forum, but to post their answers so everyone can follow the thread. 

I have asked Derek to post the content of his PM (and hopefully answer the basis question. 

Many thanks,

Gareth. 

Engine turns normal no drop in battery voltage just turns then eventually fires after that car is fine , in the summer the car starts ok so am check supply feed starting with fuses in the boot on top of the battery then investigate forward 

At the moment I have removed the glow plug module to test voltage supply I have checked the glow plugs resistance for all plugs is 0.1 ohms I have checked continuity of Reed wires to the plugs no breakages resistance is zero this reading is taken from the tip of the supply cables back to the module mounting socket. Should I have the ignition on when I test voltage from battery I believe this voltage goes through the engine management module before it gets to glow plug module ?

Hello Derek,

I would say you need to have the ignition switched on when you do the voltage check. If this all proves to be serviceable, to my mind, I would think you have been as thorough as possible with the DIY work and checks you could be expected to do. 

With serviceable glow plugs, and the engine turning over enthusiastically ( and starting OK when hot, but not cold) then if it were, I think I would now be investing in an hour’s labour at a trusted local diesel specialist to investigate further - possible injector issues?? 

For ‘trusted local diesel specialist’ I normally suggest asking for recommendations at your local taxi rank - these chaps depend on such contacts. Unfortunately, I doubt whether you are going to get many taxis on the rank in these troubled times. 

Kind regards,

Gareth. 

Thanks as I am a retired diesel mechanic 🚌 public service vehicles I ain’t going to give up yet I have a brand new 457 glow plug module to fit plus I have a few avenues to investigate will keep updates coming for other members 

Possible fix I have been using Tesco diesel it does not contain an additive it’s also bio fuel which forms crystals in the fuel filter thereby restricting fuel flow , so am going to change the fuel filter then use a diesel anti wax additive to prevent the crystals forming fingers crossed, ps I am a retired HGV mechanic and have come across this before on trucks but never on modern cars 

Ok further to my previous comments I have no feed to the glow plugs I hooked a circuit tester from the glow plug feed cable to earth no voltage in fact I have no voltage at terminal 30 in the relay housing this should be battery voltage 12 volts why have I not ? All fuses on the battery are intact . No fault codes are shown , Any thoughts please the car still starts but not without turning over for about 10 - 15 seconds

Ok further to my previous comments I have no feed to the glow plugs I hooked a circuit tester from the glow plug feed cable to earth no voltage in fact I have no voltage at terminal 30 in the relay housing this should be battery voltage 12 volts why have I not ? All fuses on the battery are intact . No fault codes are shown , Any thoughts please the car still starts but not without turning over for about 10 - 15 seconds

More progress terminal 30 must have 12 volts ignition feed it does not but also found out there should be a relay j317 it supplies power to terminal 30 so could this be the fault anybody know the location of relay j317 ?

Result  look a what’s missing in these photo 1 is my car the other is my next door neighbour car

A dirty great big 50 amp fuse S39 engine glow plug strip fuse it’s not on the battery it’s in the poxy fuse box so why is it missing that’s the next question 

Sorry to jump on your post but where is that fuse box located? I know there’s one in either side of the dash? X 

Below is the engine wiring for CAGA engined aA4 S39 is the glow plug 50 amp strip fuse that is in the engine fuse box under the ECUB8 CAGA Engine wiring.pdf

I have this exact problem right now, did you finally cure this? first start of the day only in winter it cranks for 10-15 secs then finally starts, after this it starts within 1 second for the rest of the day.

I changed my glow plugs and it made a difference for a day or two but then the glow plugs all went open circuit, so I changed them again and yet again they all went open circuit so I'm now going to change the glow plug relay (Ive already checked the 60a fuse and its fine)

Edited January 22, 20233 yr by exiledweegie123