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Octavia Heater Problems & Noises (1.9 TDI)

 
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Octavia_4x4
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Post20-12-2009, 12:30    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

Hello,

What comes standard with the ATD engine? Does the German version have a coolant preheater, i.e., the water flange with the three glow plugs? My upcoming Octavia, which is an import from Italy, doesn't have the heater, but the parts are available.

My current SEAT 1.9 TDI has it; there, the water is already warm after 6-7 km, even at -10°C. In the Octavia, the temperature gauge only moved from 0 yesterday after 15 km...

Therefore, I'm considering whether to spend approximately €17 on the water flange, around €50 on the heater housing, and about €15 on the three glow plug connectors, and then retrofit those parts.

Has anyone ever done this before? Is it even possible to make the connection without any problems?


According to the wiring diagram, I still need the relays for high/low heating power, which will then be activated using 2 pins via the engine control unit (ECU).


Has anyone ever done this before?



And the current problem is this: the car makes a roaring noise when accelerating, especially at higher RPMs (up to 2000 RPM) when giving it full throttle.


Excluded were:

- Exhaust system (no issues reported, despite having 200,000 km).
- The exhaust system/bodywork is not the issue.
- The intercooler piping is sealed except for the pipe in the right wheel well, where there is slight oil residue at the connection point.
- No error codes stored.
- No driving behavior deficiencies.


Does anyone have a diagnostic approach for this?


Translated on 21-08-2026, 9:42.
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RedR32
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Post20-12-2009, 21:54    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

Is it worth it? It's better to install heated seats icon_biggrin.gif and drive with reasonable speed icon_biggrin.gif.
The Mother's Ibi with an ATD engine also has a coolant heater, but it was sold new in Luxembourg. I think all the models released in Germany have a coolant heater.
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Translated on 21-08-2026, 9:45.
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Octavia_4x4
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Post20-12-2009, 23:14    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

RedR32 wrote:
Is it worth it? It's better to install heated seats icon_biggrin.gif and give it plenty of power icon_biggrin.gif
.

It's all ready; I finished wiring it today. It's not about warm air for me; the Octavia has PTC heating elements in the ventilation system, so warm air comes out immediately. My concern is engine wear.

"Whether it's worth it is relative, but I think so. My Ibiza, which has an identical heater with the same part numbers, heats up about three times faster."

"And the heater flange costs around 30 euros when bought from a used parts supplier. You also need to factor in the relays, some wiring, and about 2-3 hours of tinkering. I'm definitely going to try it; I looked at all the wiring diagrams today, and it seems pretty straightforward."

"Specifically, it's the relays for low/high heating power that are located in the relay box in the engine compartment of the Octavia, along with two control wires to the engine control unit (ECU), and then the three glow plug wires leading to the glow plugs."

Now the question is: Does one need to activate the auxiliary heater in the MSG (Multi-System Generator), or does it automatically turn on? The MSG only provides two positive control wires, one for activating the low heating power and one for activating the high heating power.


Translated on 21-08-2026, 9:47.
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Post20-12-2009, 23:26    Subject: Octavia Heater Problems: Noise & Solutions (TDI) Quote

Ibiza1986 wrote:
...
Therefore, I'm considering whether to spend approximately €17 on the water flange, around €50 on the heater housing, and about €15 on the three glow plug pins, and then retrofit those parts.


Absolutely!

Quote:

And the current problem is this: the car makes a roaring noise when accelerating, especially at higher RPMs (up to 2000 RPM) when giving it full throttle.


It is generally considered normal in the context of ATD/AXR.
They are often referred to as "drone enthusiasts." Some seem extremely dedicated, while others probably aren't. So, I wouldn't go overboard searching for them. icon_rolleyes.gif
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Translated on 21-08-2026, 9:50.
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Post21-12-2009, 0:03    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

Hmmph...

He is louder than my ASV... icon_confused.gif I used to think he sounded quieter, but that might be my imagination. Of course, Skoda has probably saved money on the insulation as well...

"What I will definitely replace is the AGR (Abgasrückführung system), because it's leaking oil."


Just out of curiosity, what's causing the engines to be so loud right now?


Translated on 21-08-2026, 9:51.
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Post21-12-2009, 0:05    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

Ibiza1986 wrote:
What I will definitely replace is the EGR valve, because it's leaking oil...

Don't replace, seal it up, seal it up... *Sing, Sing...* icon_lol.gif icon_lol.gif
MfG. Michael

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Translated on 21-08-2026, 9:52.
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Post21-12-2009, 0:23    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

I've been waiting for this. icon_lol.gif However, it doesn't help; there's oil leaking from the guide flange of the shut-off valve shaft and on the other side from the membrane ambient pressure hole. The only solution is to replace it...


Translated on 21-08-2026, 9:53.
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Post21-12-2009, 13:02    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

It would be completely nonsensical to disable the EGR system if you are complaining about temperatures being too low further up in the text.
Gruß Christian
A6 BPP, Ex-A6 AKN (Gurke), Ex-Audi100 92 AAT (5Zyl.)


Translated on 21-08-2026, 9:53.
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Post21-12-2009, 13:12    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

christians wrote:
It would also be completely ridiculous to disable the EGR if you are complaining about temperatures being too low further up in the text.

Who always claims that the engine takes longer to warm up without EGR? I removed the EGR from both my ACV and my ARL engines. I couldn't detect the slightest difference with the same temperatures and driving style (I drive very consistently). Both were equally warm after the same distance, whether with or without the EGR system. My ACV has no EGR, auxiliary heater, or glow plugs in the water circuit, and it reaches 90°C (79°C actual) after 10 km at -15°C.
MfG. Michael

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Translated on 21-08-2026, 9:54.
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Post21-12-2009, 13:22    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

Closing an AGR account is something I wouldn't do, and it's not even a legal consideration for me.

I'll check in the next few days to see if I can remove the entire auxiliary heater directly from a Golf IV at this junkyard.

Greetings.
George.


Translated on 21-08-2026, 9:55.
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Post21-12-2009, 14:39    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

TDI-GTI-4-Motion wrote:

Who always claims that the engine warms up worse without an EGR system?

For example, I...
I tried it myself, and it makes sense from a logical perspective.
Gruß Christian
A6 BPP, Ex-A6 AKN (Gurke), Ex-Audi100 92 AAT (5Zyl.)


Translated on 21-08-2026, 9:56.
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Post21-12-2009, 14:50    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

Sure, because the intake air is colder when the EGR system is deactivated. This allows preheated exhaust gas to be reintroduced into the engine, which helps to quickly warm up the intake and combustion chambers... it's actually quite logical.

The only explanation I can think of is that you tested it in a larger 2.5 TDI, and that the engine's size and the resulting heat dissipation might not be impressed by the relatively small AGR (Adjustable Geometry Turbocharger).

This might be an explanation for your ACV (Air Conditioning Valve)... but it's strange that it happens on the 1.9 ARL engine as well.


Translated on 21-08-2026, 9:57.
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Post21-12-2009, 15:46    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

It is always difficult to objectively assess subjective feelings. A malfunctioning EGR valve *must* have an influence, as it introduces thermal energy into the process. However, this effect can certainly be observed more or less frequently in road traffic, because who has the chance to experience exactly the same conditions twice, other than when the EGR is either on or off?

I also consider the retrofit for the heating system to be quite simple. The control unit is mounted higher up near the expansion tank (on the 1J model), the cables are integrated into the wiring harness, and it should work!


Translated on 21-08-2026, 9:59.
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Post21-12-2009, 16:33    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

Ibiza1986 wrote:
Sure, because the intake air is colder when the EGR system is deactivated. This allows preheated exhaust gas to be reintroduced into the engine, which helps to quickly warm up the intake and combustion chambers... it's actually quite logical.

Well, it's not well thought out. Also consider what the main function of the EGR system is. Correct, to lower the combustion temperature. And the cooler the exhaust gases, the better the efficiency of the EGR. There's a reason why some vehicles have an EGR cooler. Without EGR, the combustion temperature is slightly higher. Therefore, in the end, it probably doesn't make much difference.
MfG. Michael

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Translated on 21-08-2026, 10:00.
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Post21-12-2009, 17:04    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

matthiasTDI96 wrote:


I also consider the retrofit for heating to be simple; the control unit is mounted higher up near the expansion tank (on the 1J), the cables are integrated into the wiring harness, and it should work!


Okay, it's actually quite simple. There are two positive control wires going to the relays that I need to connect to the motor control unit (or they might even be pre-wired, who knows, I'll have to check). Then, from the relay, one wire goes to ground, and the other connects to the 50A fuse on the battery for the glow plugs (at least, that's where it should go according to the wiring diagram). Finally, there's a cable harness with three glow plug connectors that needs to be connected to the water flange.

I think it takes about an hour.


Translated on 21-08-2026, 10:02.
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Post21-12-2009, 17:11    Subject: Octavia Heater Problems & Noises (1.9 TDI) Quote

TDI-GTI-4-Motion wrote:
Also, consider what the main task of the EGR valve is. Correct, it's to reduce the combustion temperature.

I used to think the same thing whenever I read that deactivating the EGR system could lead to slower warm-up times.
With more O2, the combustion becomes hotter, and this heat is transferred (partially) to the water circuit. However, the heat that I channel into the intake manifold via the EGR system does not heat up this water circuit (except in the case of EGR cooling). The lower lambda value "cools" the combustion process.
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Translated on 21-08-2026, 10:03.
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