Seriously? 10 codes at once?

[believer007]

I've done some searching, and hit all of the obvious things....fuses, cleaning grounds, etc...

The car starts and idles fine, sounds great. pull up VCDS, get 5 codes...save them, clear them, get 10 CODES! Save them, clear them, get 1 code (EGR). Clear it, get 10 codes (showing duplicates, which I find odd too), clear it, get 5 codes...very odd...

No mice issues, good grounds...ECU take a dump?

Tried hard format (tied both battery leads together, disconnected, of course), still pissy.

It is my sister's car, an hour away, so I didn't have everything that I needed to fish through the wiring loom, but the ECU leads look as new. Checked and replaced the usual suspect relay's with known good ones, no difference.

Anyone have experience with this total puking of codes?

Thanks!

Tuesday,04,November,2025,14:17:04:10369
VCDS Version: Release 25.3.2 (x64) Running on Windows 10 x64
www.Ross-Tech.com

Address 01: Engine Labels:
Control Module Part Number:
Component and/or Version:
Software Coding:
Work Shop Code:
VCID: 55ED0257AC29D733D0-4B3C
Fault Codes have been Erased

10 Faults Found:
17957 - Boost Pressure Regulation Valve (N75)
P1549 - 35-10 - Open or Short to Ground - Intermittent
18027 - Glow Plug Relay (J52)
P1619 - 35-10 - Open or Short to Ground - Intermittent
17946 - Fuel Shutoff Solenoid (N109)
P1538 - 35-10 - Open or Short to Ground - Intermittent
17849 - EGR Valve (N18)
P1441 - 35-10 - Open Circuit or Short to Ground - Intermittent
17660 - Commencement of Injection Valve (N108)
P1252 - 35-10 - Open or Short to Ground - Intermittent
17957 - Boost Pressure Regulation Valve (N75)
P1549 - 35-10 - Open or Short to Ground - Intermittent
18027 - Glow Plug Relay (J52)
P1619 - 35-10 - Open or Short to Ground - Intermittent
17946 - Fuel Shutoff Solenoid (N109)
P1538 - 35-10 - Open or Short to Ground - Intermittent
17849 - EGR Valve (N18)
P1441 - 35-10 - Open Circuit or Short to Ground - Intermittent
17660 - Commencement of Injection Valve (N108)
P1252 - 35-10 - Open or Short to Ground - Intermittent

Readiness: N/A

 

[STDOUBT]

I'm facing the same thing on my project car. I am thinking ECU myself.
Done some reading and there have been cases where the solder inside the ECU, on the PCB develops cracks.
It's repairable if you're a soldering iron jockey, and have really good magnification. Need a 700 degree iron though, and to know your solder.
I'm struggling to find a good source for a reconditioned ECU. Throwing a used one in seems like it'd just be a time bomb.
...Or it could last forever.
Like you, I've gone through all the grounds, fuses, the "hard format" and it's code-city. Crazy.

 

[Matt-98AHU]

Most of those items share a fuse. So, not only look for a fuse being blown, but also make sure you have all the fuses you're supposed to in the correct locations...

I've seen this resolved more than once by simply installing a fuse where there wasn't one for some unknown reason... Some previous person checking the fuses and put one in the wrong slot, and left a slot open that wasn't supposed to be, usually.

Check real closely for fuse position #34 on the side of the dash. There should be a 10A fuse there.

The only thing on your code list *not* powered by that fuse is the glow plug relay.

MAF
N18
N75
N239
N108

All on fuse #34.

Now, the n109 is powered directly by the ECU. So, seeing that code could be a wiring issue between ECU and solenoid, *or* fuse 32 (30A) could also be missing. I've seen some weird stuff where, despite that fuse powering the quantity adjuster and the ECU itself, there somehow ends up being power that can get back fed through the quantity adjuster and be *just enough* to power the ECU, until you go to start it. The voltage drop then causes the ECU to turn off entirely again as the loss of voltage is below the threshhold where it just shuts off.

And, of course, the ECU doesn't set a code for being de-powered due to undervoltage--but other modules will set a code for intermittently not seeing the ECU! Which just leads to my next point: it never hurts to ping other modules in the car to see if they are storing codes that could add context/clues to what's going on.

 

[believer007]

I'll triple check those fuses, AGAIN...I did not think about the part about someone leaving one out!

One other odd thing is that the passenger side headlight (just replaced by a shop), is on, but dim...

Thanks!

 

[wonneber]

I'm facing the same thing on my project car. I am thinking ECU myself.
Done some reading and there have been cases where the solder inside the ECU, on the PCB develops cracks.
It's repairable if you're a soldering iron jockey, and have really good magnification. Need a 700 degree iron though, and to know your solder.
I'm struggling to find a good source for a reconditioned ECU. Throwing a used one in seems like it'd just be a time bomb.
...Or it could last forever.
Like you, I've gone through all the grounds, fuses, the "hard format" and it's code-city. Crazy.

I'm facing the same thing on my project car. I am thinking ECU myself.
Done some reading and there have been cases where the solder inside the ECU, on the PCB develops cracks.
It's repairable if you're a soldering iron jockey, and have really good magnification. Need a 700 degree iron though, and to know your solder.
I'm struggling to find a good source for a reconditioned ECU. Throwing a used one in seems like it'd just be a time bomb.
...Or it could last forever.
Like you, I've gone through all the grounds, fuses, the "hard format" and it's code-city. Crazy.

If you use a 700 degree iron soldering iron you may melt the ECU board.
I use do (some) circuit board component repair when boards easier to solder IF you can find the component's..
Today they wave soldering components and pins may not even go through the board.

 

[Matt-98AHU]

It is good to note I *have* seen maybe 2 ECUs setting similar codes, and it was infact the ECU.

Easy thing to do is simply check a couple of those items, easiest to reach probably being the N18 and N75, and see if pin #1 (black/yellow wire) has 12V with the key on.

If you are getting 12V, but still have those codes that come back right after clearing, you are more likely looking at an ECU...

Verifying a couple simple things like that first before condemning the ECU is usually the best route. Eliminate as many possibilities as possible before condemning.

A failed ECU is plausible, just not that common. But, I have seen it before.

 

[P2B]

If you use a 700 degree iron soldering iron you may melt the ECU board.

Actually 650-700C is the ideal setting for reflow work. Maximum setting on my Weller station is 850C.

 

[TurboABA]

10 Faults Found:

Amateur!

2025-01-24 -- 206 Faults Found -- 2025 Q6 (USA)
2025-01-25 -- 330 Faults Found -- 2025 Q6 (USA)
2025-01-27 -- 344 Faults Found -- 2025 Q6 (USA)
2025-02-04 -- 370 Faults Found -- 2025 Q6 (USA)
2025-02-08 -- 386 Faults Found -- 2025 Q6 (USA)
2025-02-25 -- 550 Faults Found -- 2025 A5 (Germany)

 

[P2B]

A failed ECU is plausible, just not that common. But, I have seen it before.

Based on posts here over the last couple of years failed MK4 ECUs seem to be becoming a bit more common. Haven't encountered one myself yet.

 

[Matt-98AHU]

Based on posts here over the last couple of years failed MK4 ECUs seem to be becoming a bit more common. Haven't encountered one myself yet.

A bit, maybe. But, proper diagnostic path would be to eliminate all other possibilities before blaming the module. And in this case, it's pretty easy to do. Just see if you're getting voltage where you're supposed to, key on engine off, if not, fix that problem, then re-evaluate. If you *are* getting voltage, technically the next thing would be to check continuity for the other wire back to the ECU (ECU duty cycle switches ground to control all these solenoids). But, realistically, when you have a code for all these at the same time, it's usually a shared power source that is the fault, as I outlined. But, it can occasionally be the ECU, it's just the last thing you want to assume. Eliminate as many other possibilities as you can before assuming that.

 

[wonneber]

Actually 650-700C is the ideal setting for reflow work. Maximum setting on my Weller station is 850C.

I didn't notice you were in Canada.
Metric.

 

[P2B]

I didn't notice you were in Canada.
Metric.

Oh, you mean 700F is too hot? That's barely enough to melt solder.

 

[TurboABA]

 

[believer007]

All great ideas...
From the man, the myth, the legend, Franko6:

"Best guess, you have wires crossing up in the engine harness.
Most likely place is where it goes from the engine to the left fender. There is a zip tie built into the plastic tunnel going up to the firewall. Where it flexes at that point, insulation will abrade or crack.

most of your codes are related to the engine harness. The EGR valve has another abrasion location against the firewall near a corrugated wire covering near a tee. Pull the wires out from the corrugation and see if they are rubbed bare."

I haven't had a chance to get back into the car, but I'll check there and post back...

 

[STDOUBT]

Obligatory

Silly-stuff-metric-system.jpg

• STDOUBT
• Sep 18, 2020

 

[Sting]

Obligatory

Silly-stuff-metric-system.jpg

• STDOUBT
• Sep 18, 2020

Yes, but they still used the metric system to get to the moon. It's a scientific standard. A Mars probe that crashed a few years back was because some kid used imperial units.

Just saying