P0381 Glow Plug/Heater Indicator Circuit

Skimaster

Member
Joined
Nov 18, 2019
Location
Utah
TDI
2003 Jetta wagon 1.9T
I just acquired a 2003 TDI Jetta wagon. Noticed the check engine light and glow plug light wouldn't light up ever. pulled the dash apart and found TP shoved in the MIL hole and the glow plug light desoldered on one side. I resoldered the glow plug light and removed the TP. Now both the lights work.

I am getting a "P0381 Glow Plug/Heater Indicator Circuit" code. Everyone seems to get the P0380 code, so I checked the glow plugs and they all have exactly .4 ohms of resistance and look brand new. I checked the harness and contacts look brand new. I pulled the relay and it also looks brand new.

I'm guessing the previous owner chased this issue and couldn't figure it out and just desoldered the one LED and put tissue paper in front of the MIL light.

The code states "indicator". Is it referring to the LED in the dash? I cannot find anybody online with the P0381 code in an MK4. I cannot register the vehicle here in utah till I get this fixed. Any input on a direction to go would be very helpful
 

Skimaster

Member
Joined
Nov 18, 2019
Location
Utah
TDI
2003 Jetta wagon 1.9T
yes. the code doesn't come back immediately, it seems to take few drive cycles.

The glow plug light is also blinking.

Are you supposed to feel the glow plug relay click when you turn the key on? Because I disconnected the temp sensor to make it turn on and I cannot feel it click.
 
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STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
ALHx2
First, P0381 is not a VCDS code so you're using a generic scanner.
If any of these guys are still around, they can scan it properly and get you a better
idea of what's wrong:
Autobahn Service Center
1358 West 400 South
Orem, UT 84058‎
(801) 374-0012
Alpine Foreign Repair
341 East 900 South
Salt Lake City, Utah 84111
(801) 355-6459
Dan @ The Car Doctors
(801) 766-4449
2158 Redwood Rd
Saratoga Springs, UT 84045
In the mean time, you really should inspect carefully all the ridiculously delicate wiring VW put
in your car connecting the GPs to the rest of the system. Most likely you're looking at a short to
ground or power.
OTOH............have you tried just clearing the code? (nm)
 
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Skimaster

Member
Joined
Nov 18, 2019
Location
Utah
TDI
2003 Jetta wagon 1.9T
I didn't realize the generic code reader would yield such different results. I connected my knockoff vcsd cable and read the codes after clearing them. These both both come back on immediately after clearing them.

2 Faults Found:
16955 - Brake Switch (F): Implausible Signal
P0571 - 35-00 - -
19561 - Shareware Version. To Decode all DTCs
P3105 - 35-10 - Please Register/Activate - Intermittent

I'm guessing the 16955 is why my cruise control isn't working. Probably the brake switch?

The 19561 probably explains why there's a funny noise when I shut off the vehicle?

Why would the Glow plug light keep blinking indefinitely?

Other than that, all my emissions readiness monitors are complete and no EOBD related dts are set, so I am good to pass utah emissions tomorrow I think!
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Daughters car, 2005 Golf TDI Mine, all 5 spds
If the former owner was chasing a flashing glow plug light, thinking it was the glow plugs he was probably barking up the wrong tree.

Here is a list of possible problems that make that little light flash.

Flashing glow plug light

The flashing glow plug is sort of a super "check engine light". It flashes when the ECU detects that certain very important components are out of spec.

Per a post by MoGolf, the codes that cause a flashing glow plug light are below.

00741 Brake pedal monitoring - implausible signal
01044 Control unit incorrectly coded
16705/P0321 Engine speed sensor - implausible signal
16706/P0322 Engine speed sensor - no signal
16955/P0571 Brake light switch (F) - implausible signal
17653/P1245 Needle lift sender (G80) - short to earth
17654/P1246 Needle lift sender (G80) - Implausible signal
17655/P1247 Needle lift sender (G80) - Open circuit/short to positive
17762/P1354 Modulating piston movement sender (G149) - electrical fault in current circuit
17969/P1561 Metering adjuster (N146) - control difference
17978/P1570 Engine control unit blocked
18020/P1612 Control unit incorrectly coded
18026/P1618 Glow plug relay (J52) - short to positive
18027/P1619 Glow plug relay (J52) - open circuit/short to earth
18040/P1632 Accelerator position sender - voltage supply

Here is the Ross-tech wiki for that code.

http://wiki.ross-tech.com/wiki/index.php/16955/P0571/001393
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Or someone jammed the wrong bulb in the back. Given the previous owner's doofus approach to repairing the cause of the light in the first place, that is entirely possible.
 

Skimaster

Member
Joined
Nov 18, 2019
Location
Utah
TDI
2003 Jetta wagon 1.9T
I replaced the brake switch and cleared the codes and it come right back on immediately.
The third brake light was out so I pulled it apart and found some bad solder joints. Resoldered the joints and the light now works. Cleared the codes and it still comes right back on again.
Found out both the 5007 bulbs in the rear for the running lights were out, so I replaced those. Cleared the code and it hasn't come back on yet.

Now onto the 19561 code. Probably check the wiring first since that will supposedly wear out.

The engine takes a while to get up to temp, but won't hold temp when at highway speeds. I'm guessing the thermostat is stuck open.

Once it gets up to temp, the engine has a hiccup/misfire feeling every couple seconds. I know all the injectors were rebuild by DBWllc recently. What direction should i go with this? Will the 19561 code have anything to do with that?
 
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