Glow Plug Heater Not Working, 1.4 TDI [AMF]

Hello!

After the temperatures dropped below freezing again, I was once again frustrated this winter with the poor heating performance of the 1.4 TDi (AMF) engine, installed in my Seat Arosa manufactured in 07/00 and equipped with glow plug heating. I'm now at the end of my knowledge; here's the connection:

Engine control unit:

045906019M, 1.4L, R3 EDC, 0000SG, 1043, Coding 0002.

- no memory errors.
- all relevant sensors consistently provide plausible values, e.g., [coolant: -3.5; air: -1.9; fuel: -2.8].
- Generator utilization: 38%
- Regarding the actuator diagnosis, the relay for low and high heating power is activated -> Water is visibly boiling.

However, in measurement block 16 (field 2), the digit in the 8th position is always set to 1, which indicates that either the coolant temperature is above 70 degrees Celsius or the intake air temperature is above 5 degrees Celsius. In field 3, which corresponds to the two relays, the value is set to 00.

What is the reason for that?

- Still not cold enough?!
- Are there different or incorrect threshold values stored in the control unit, since different values apply for the "PTC auxiliary heater" option in the heat exchanger?
- Can the glow plug heating system be somehow programmed or coded?
- Incorrect engine control unit?

I would be grateful for a technically precise answer!

Best regards, Maurizio.

Hello!


- all relevant sensors consistently provide plausible values, e.g.,

You're excluding both of those possibilities with your previous post, ruling them out as potential causes.
Possibly a software error in the control unit?
IF CONDITIONS = TRUE AND FUNCTION = 0 THEN STG IS FAULTY ?!

Hi,

ich dachte bisher auch, dass mit meinen Glühstiften etwas nicht stimmt. Ich habe daher nach einer kalten Nacht heute Morgen den Motor bei -2,5°C zwei Test-LEDs mit den Glühstift-Relais verbunden. Erresult:

Ignition on: Both LEDs off.
Climatronic set to high: Both LEDs are off.
Climatronic set to 20°C: Both LEDs off.
Engine on in low gear: Both LEDs are off. (I thought: "Damn! Something's broken!")
Playing around with the Climatronic settings: Both LEDs remain off.
Started up: Shortly after: first LED lit up. (Joy!)
Playing around with the Climatronic (varying temperature and fan speed, turning the Climatronic off): the first LED remained on.
A short time later: the first LED turns off, the second LED turns on. (Surprise)
Later, after traveling approximately 2 kilometers: both LEDs are on.
Played around with the Climatronic settings: No effect on the LEDs.

In this case, by "a short time," I mean less than 30 seconds.

I suspect that the engine control unit initially activates one glow plug shortly after starting, then two, and finally all three, in order to avoid putting excessive strain on the battery immediately after starting (due to things like the fan, windshield heating, and glow plug afterglow, etc.).

As far as I can tell, the glow plug heating is independent of the Climatronic system. (It would be possible that the heating provides more heat if the driver wants to warm up the interior.)

Regards,
Sure, here is the translation of the text from German to English:

"Micha"

Hi,

If you want to know more precisely, you could connect an LED to the heating element. It's likely that the first heating stage will be activated shortly after the post-bonding process ends...

Best regards,

Jan.

...furthermore, to the best of my knowledge, there are speed limits that affect the preheating process.

I have something about "starting below 970 RPM" in mind. (No guarantee, especially not for the AMF, whether that's actually the case).

So, if you're measuring while the vehicle is stationary, it will never turn on!

m;