Electrical- Glow plugs & Low voltage supply

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Thomas R

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Hi,

I'm wondering if anyone can give any information/advice on an issue I'm having with a B7 Avant. I had an intermittent engine management warning light and upon inspection noticed it was glow plug related, I changed the glow plugs as a first point of call and had the car scanned again with VCDS.


I now have the following fault code on all glow plugs;
001652 - Cylinder 4 Glow Plug Circuit (Q13)
P0674 - 006 - Electrical Fault - Intermittent - MIL ON
001650 - Cylinder 2 Glow Plug Circuit (Q11)
P0672 - 006 - Electrical Fault - Intermittent - MIL ON
001649 - Cylinder 1 Glow Plug Circuit (Q10)
P0671 - 006 - Electrical Fault - Intermittent - MIL ON
001651 - Cylinder 3 Glow Plug Circuit (Q12)
P0673 - 006 - Electrical Fault - Intermittent - MIL ON

I also have fault codes on ABS & ICE relating to low voltage supply.
Could these issues be related?

Also before I start playing around, has anyone experienced these before? What did you find it to be.


Thanks for reading and hopefully you guys can share some knowledge on this. It's driving me insane!!!!
 
I'd start by checking the condition of the battery
 
Hi there when the car was scanned with vcds was the codes cleared? As retroman said I'd check your battery and alternator voltages first then the fusebox for water damage.
 
Hi, to revisit this.
The car was scanned before Christmas, cleared, then came back again 2-3 days later.
Scanned it again last week after changing 614 relay, cleared, left it 4 days as I was working away, started it on my return and it's back again.
Battery and alternator voltages are fine. There doesn't appear to be any water damage and fuses look okay.

We swapped the glowplugs over when I first experienced this, the guy had used 2 Bosch plugs and 2 different brands.
We put 4x Bosch ones back in, using the product code on one of the originals.

After reading various threads on the web my car "should" run with NGK plugs.
I know it's a long shot Do you think the different brand could be the reason for the fault?

Failing this, I'm looking at a new glow plug control module before it goes into Audi for diagnostics

Any further opinions?


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Different brands shouldn't make any difference as long as they are the same specification.
What is the code on the original NGK plug and the Bosch items
 
I don't know what the code is from the original as they were 2x Bosch and then 2 separate brands.
I used the Bosch product code to order more.

I need to pull one back out to ensure they're the correct ceramic ones but I couldn't see how using the wrong type of plug would give me an intermittent fault. To me using the wrong type would either work or it wouldn't.


I'll pull the plug out and let you know what the product code is:)


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I know I'm harping on about battery/holding a charge :haha: but bearing in mind the totally unrelated ABS/ICE error codes it does make me suspicious. I've actually seen this several times, if a battery is failing to hold a good charge or is not "man enough" for the job, the ECU will ration out its power so that basic starting and running facilities will continue. Things like ABS, ICE, central locking and alarm systems are deemed "non-critical" and will start throwing vague error codes about lack of voltage. Somebody in the past has economised by replacing just a couple of glow plugs - is it possible that the battery was replaced by something not as powerful as the OE and which is not providing the total power necessary during this colder weather?
 
Retroman- I read your last post and did think it made sense so I went and pulled the battery out of my old mans A3. So the battery that was in the car was around a 70, dads is a 62 and apparently the B7 requires an 80
Swapped them over, cleared the code- Great. The new battery meant my driver info was not present, then my central locking wouldn't work, then it all came back and was great.

Today makes it around 2.5 days since I cleared the code, it's back again. What's strange is the code doesn't appear instantly or even after restarting the car a number of times, it always appears to be 2-3 days before it reappears. Now I'm happy to go down the route of replacing the battery for an 80 but based on the delay for the code returning do you still think that could be the issue?
 
Thomas R said:
Retroman- I read your last post and did think it made sense so I went and pulled the battery out of my old mans A3. So the battery that was in the car was around a 70, dads is a 62 and apparently the B7 requires an 80
Swapped them over, cleared the code- Great. The new battery meant my driver info was not present, then my central locking wouldn't work, then it all came back and was great.

Today makes it around 2.5 days since I cleared the code, it's back again. What's strange is the code doesn't appear instantly or even after restarting the car a number of times, it always appears to be 2-3 days before it reappears. Now I'm happy to go down the route of replacing the battery for an 80 but based on the delay for the code returning do you still think that could be the issue?
Click to expand...



To add to this further. Today has been the first day I've done a complete scan of the car since changing the batteries over-
-Intermittent electrical fault on all four glow plugs- as expected
-no fault on the ABS(unlike my existing post)
-01826 - Sensor for Steering Angle (G85); Supply Voltage Terminal 30--- This I haven't seen before
- Radio has 4 intermittent faults
-Navigation has the same 4 faults as above


I know I'm answering my above question here but based on what you have said above I'm guessing that the 70 & 62 batteries may be too weak for the job.

Get back to me if you have anything else to input, in the meantime I'll get a replacement 80 battery ordered.
 
The ECUs in modern cars are closely “paired” with the OE batteries fitted. So if your OE battery was say 80 AH (Amp Hours)– this denotes the energy capacity that the battery can store. The ECU will distribute this power supply to the various electrical components in the car. If you suddenly introduce a battery with a reduced capacity of say 60 AH, the ECU will not know what has happened and will simply assume that the capacity of the OE 80AH battery has reduced because it is failing/faulty. If you change the battery it should be for one with identical spec to the OE one. It’s my educated guess, from a forum perspective, that this is your problem – given the random and vague nature of the faults you are getting. In any event, it is not a waste of money to get the correct battery installed and be able to properly eliminate it from possible problems – however, if I fancied a gamble, I’d put £10 on the battery :haha:
 
Retroman-
I replaced the battery on Saturday with a new one purchased directly from Audi-Ouch!! Scanned the car and faults cleared.
Yesterday was 2.5 days and upon starting the car after work- Light back on!!!!!!!
I've just scanned the car again and all faults are present but now the error reads
001649 - Cylinder 1 Glow Plug Circuit (Q10)
P0671 - 006 - Electrical Fault - MIL ON

Instead of electrical fault- intermittent- Mil on.

My intentions are to check the glow plug wiring this weekend, although I don't think it's entirely down to that as the product is not isolated to the glow plug area.

Anyway, at least I don't have to fulfil the £10 wager on top of the over priced Audi battery ;)
Any further ideas mate?
 
Well a fault in the glowplug wiring could cause your problems if it's shorting. Let us know how the test goes
 
For those that have been following this-
I purchased a set of NGK Ceramic glow plugs last week(The car had brand Bosch metal ones in as that was what was supplied from the dealer using my REG details, it looks as if the previous owner did the same as the car had a mix of plugs in when I bought it).
Fitted them & Cleared the fault code Saturday and it appears to have done the job(fingers crossed)
 
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Glad it seems that you have got there in the end. There is a big difference between the metal and ceramic plugs from the point of view of the glow plug controller. It's usually OK to mix brands of plugs but they have to all be the same type and specification.
 
desertstorm said:
Glad it seems that you have got there in the end. There is a big difference between the metal and ceramic plugs from the point of view of the glow plug controller. It's usually OK to mix brands of plugs but they have to all be the same type and specification.
Click to expand...


So it would seem. I had wanted to change the plugs for a while but under advice didn't bother with it, my change of heart was after reading a thread on pistonheads on how Audi do things a certain way for emissions.

Anyhow, lets hope the issue is resolved and this one is put to bed!
 
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