Common TDI CEL causes?

spongebob

Veteran Member
Joined
Mar 22, 2002
Location
Mesa, AZ
TDI
Not anymore.
What are some common causes of CEL on TDIs?

30 days ago I had an intermittent CEL taken care of, replaced a faulty coolant temp sensor and the light went away... Until today, I have another CEL. :mad:

Only thing different lately is I'm down to the last 2-3 gallons of the first tank of biodiesel I've run in four years. I know BD can send fuel tank sediment buildup from D2 use into the fuel filter. Would a fuel filter issue cause a CEL, or is this likely the glow plug bridge or something else?
 

mrGutWrench

Top Post Dawg
Joined
Aug 29, 2002
Location
Carrboro, NC
TDI
'03 Jetta Wagon, 5-speed, 563K Miles (July '23)
oilhammer said:
No, 90% of YOUR POSTS are false positives... :rolleyes:
__. I consider a diagnostic system that's only indicating a problem with the diagnostic system to be giving false positives.
 

meganuke

TDIClub Contributor, Vendor
Joined
Mar 6, 2003
Location
VA/CT
TDI
2010 Ford Fusion Hybrid
Wow...just wow. Let us know if you find any oil reserves while your head is buried in the sand.
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
mrGutWrench said:
__. I consider a diagnostic system that's only indicating a problem with the diagnostic system to be giving false positives.
__. How do you propose the glow plug harness to be monitored by ODB? :confused:
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Hehe, Gutwrench talks like a fortune cookie. Makes you say "huh?" without really thinking about it. :p

A DTC indicating a fault in the glow plug circuit is very simple. We have tried to explain this to you, and even in light of the fact that I fix about 3 such DTCs a week successfully you STILL seem to think YOUR CAR is the only TDI in all of North America that has some mysterious German demons giving your car and only your car false DTCs (whatever those are) and that nobody anywhere can fix it. What a load of BS. You really need to sell your cars, both of them, so we don't have to listen to you dig yourself further and further into a hole week after week after week.
 
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meganuke

TDIClub Contributor, Vendor
Joined
Mar 6, 2003
Location
VA/CT
TDI
2010 Ford Fusion Hybrid
If your doctor's stethoscope is broken, do you trust him to tell you your heart is fine? Or do you replace the stethoscope?
 

BadMonKey

Veteran Member
Joined
Nov 27, 2007
Location
Colorado
TDI
2013 Focus ST
spongebob said:
What are some common causes of CEL on TDIs?

30 days ago I had an intermittent CEL taken care of, replaced a faulty coolant temp sensor and the light went away... Until today, I have another CEL. :mad:

Only thing different lately is I'm down to the last 2-3 gallons of the first tank of biodiesel I've run in four years. I know BD can send fuel tank sediment buildup from D2 use into the fuel filter. Would a fuel filter issue cause a CEL, or is this likely the glow plug bridge or something else?
95% of the codes from my car are related to the GP's or the MAFS. Only about 5% of those actually required a new part.
 

Fahrfuwerfuelen

Veteran Member
Joined
Dec 7, 2004
Location
Puget Sound
TDI
Jetta, 2005 (A4), Platinum Gray
Just my 2 cents. I've had 4-5 CELs and everytime they came out to be P0672- #2 cyl glow plug circuit. The VW techs (under warranty) are stumped and tend to agree with me that it's probably the harness, although they can't replace it until they can establish the harness is at fault.

I got one such CEL (P0672) and replaced my fuel filter cause I felt the response was not right. Right after I replaced the filter, the CEL disappeared. Go figure that one?
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
Fahrfuwerfuelen said:
I got one such CEL (P0672) and replaced my fuel filter cause I felt the response was not right. Right after I replaced the filter, the CEL disappeared. Go figure that one?
Did you check to see if the code is still there? Sometimes the CEL is thrown by a code coming a couple of times, then goes away if the code isn't thrown again in 20 starts (another figure made up on the spot- but some number of starts). However, the code may still be there. Get it scanned and let us know.

CELs go away, generally codes must be cleared.
 

spongebob

Veteran Member
Joined
Mar 22, 2002
Location
Mesa, AZ
TDI
Not anymore.
NarfBLAST said:
Spongebob, fix the problem with your radio that is preventing you from using your diagnostic port and get your car scanned!
No idea how to fix the way the radio is hooked up. I'm not tech savvy.
 

BadMonKey

Veteran Member
Joined
Nov 27, 2007
Location
Colorado
TDI
2013 Focus ST
velociT said:
And 72% of statistics are made up on the spot...

Including ^ that one.
I actually keep digital records of all the work done to any of my cars including diagnostic scans.

Thanks for chiming in with nothing to add but a line from an old Comcast commercial.
 

spongebob

Veteran Member
Joined
Mar 22, 2002
Location
Mesa, AZ
TDI
Not anymore.
Got the car scanned. Code was #2 glow plug but glow plugs tested good.

So I guess it's the 4-wire glow plug harness. Here in Phoenix, glow plugs are just to provide ECL's I guess? ;)

So I guess it's no impact on drivability, I'll just get it replaced when I can.
 

Bob_Fout

Oil Wanker
Joined
Sep 5, 2004
Location
Indiana
TDI
2003 Jetta - Alaska Green (sold) / 2015 GTI 2.0T
If it lists glowplug #2 as bad, trying test glowplug #3. On some model years, the glowplugs are number backwards.

Glow plugs are used for emissions for post-startup, and are always on for a certain period of time after engine startup.
 

midntdi

Veteran Member
Joined
Nov 8, 2007
Location
New London
TDI
2015 Golf SE 6SP
how bout a CEL that comes on when my auto tranny is in drive (but in reverse, park, nuetral there is none)

Edit: Just went to advancedauto parts and got scanned P0674 yay glow plugs
 
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