Hello,

 

I own a Skoda Octavia 1, 2002, AVU, BFQ. The problems with it started yesterday while I was driving it. I felt some jerks and immediately the EPC light came on. I got home and put the tester on. 

 The errors are those in the attachment.

 The fans don't start if the temperature reaches 90 degrees, while driving the temperature drops and you don't feel hot air if they turn on the ventilation. 

 What could it be?

check if fan spins freely by hand if it doesn't you need a new fan, if it does you need a new fan controller located under the battery tray.

Thank you for the answer. I changed the control module with the 1J0 919 506 L series with one of the Metzger brand. Likewise. I also changed the relay inscribed with the number 100, series 7M0 951 253 A. The same. I checked the 40 amp fuse above the battery, cleaned its terminals, removed the plastic battery support and checked the ground points. Likewise. I turned the fan blades. The big one rotates more easily, the small one rotates but offers some resistance. One thing: the error ONLY occurs when I start the engine. If I turn on the ignition and give Engine / Fault codes, no error appears. When I start the engine, in 5 seconds the Short to ground error appears. I delete it, after 5 seconds it appears again. This with a cold engine, without the water being at 90 degrees.

It won't let me edit the previous massage.  I will buy a new fan, instead of the one that spins harder.

If you unplug the refrigerant pressure sensor, G65, do you still get the short to ground fault?

If it spins with more resistance but still spins, the fan is on its way out so it does need replacing at some point, but it should still start. 

There is a 3 pin fan switch screwed into the radiator in roughly the bottom corner near the fan controller, they also like to fail. 

You can short out the terminals in the 3 pin plug to see if the fan comes to life, this should give you a definitive answer. 

 

If the engine reaches 90c but you're getting no warm air through hvac, I would check out temp sensor readings in VCDS and also check when the water pump has been replaced last, that's the only thing which circulates coolant around heater cores and the engine..

Thanks for the answers and directions.  I removed the plug from the AC sensor and it behaves the same way, same error.  I notice a little moisture at the plug connectors.  I will use contact spray.  I removed another plug, the one from the servo pump sensor, and I can see that it is pierced and flooded with oil, as you can see in the pictures.  I started the car with both plugs disconnected and it still shows Short to ground.  I will order the two sensors and replace them.  Now I will remove the fan block and test them.

Edited 23 October, 20241 yr by iulian_cristian
One mistake

Right now I did a test with a 12 volt battery on both fans. Both work, at both speeds. So it's not from the fans. Can you indicate the 3 pin fan switch screwed into the radiator in roughly the bottom corner near the fan controller?

I opened the plastics from wiper blades, checked the cables, removed the two plugs from the ECU, put them back, there are no signs of corrosion on the wires, apart from the servo pump sensor, everything seems fine.  So the fans work connected to the external battery but do not receive the command from the module.

I replaced the brake switch and it gives an error again.  Now it also gives an error with the throttle, in addition to the error with the fan controller which is permanent.  I drove today, the water reached 96 degrees and the fans still don't turn.  I suspect cables from the electrical network that make contact with each other.  Somewhere they touch and that's why all these errors.  I gave Output tests and when it comes to the fan test, it gives an error.  Where do you think the cause could be?

#11 is the fan switch. if you tested both fans with 12v battery you probably removed the plug for this  thermal switch. it makes the circuit when coolant reaches certain temperature. 

 

Edited 24 October, 20241 yr by WelshSkoda93

11 is not a simple temperature sensor?  I know there are two temperature sensors for the water.  This one, on the radiator and the one in the thermostat housing.  I changed this as a precaution a few days ago, but I don't think I made a very good choice (German brand but ALL PARTS made in China) because the temperature fluctuates.  I will put back the original sensor.  Now I check the wires from the plug of the fan control module to the large plug that goes into the ECU.

Only 2 wires.

You need to locate the fan switch, i gave you an example of where it was on my 1.8t. It will look very similar to what i posted earlier.

What you have there is a temperature sensor.

@WelshSkoda93 some cars don't have a radiator thermoswitch,  but use another sensor, often same PN as the coolant temp sensor, located in radiator outlet hose fitting.

Suspect the OP'S's car has this arrangement. 

@iulian_cristian can you provide the VIN so I can look up most relevant circuit info, please?

 

I changed the temperature sensor (switch) with four pins that is in the thermostat housing (I put the original one).  Same, same error.  I checked the wires from the ECU plugs, no signs of corrosion.  I also ordered the clutch sensor.  I will also check the wires from the throttle.  Serial is TMBHX41UX22576404

Thanks, yes, that confirms that you have "G83 Coolant temperature sender - radiator outlet" instead of radiator thermoswitch.

There are three fuses that feed the radiator fan control unit, cabin fuse 16 (10 Amp) and two in the battery fuseholder, the right hand blade fuse (30 Amp) for the first speed of fans, and the middle strip fuse (40 amp) for the fast speed of the fans.  Check that the black/blue wire at pin 9 of the 14-way connector has 12V when ignition is on.  I'm not sure where voltage rail "A20" originates, but it is an ignition switched supply, that also feeds the G65 sensor and some other stuff, so it seems relevant to your fault codes.

 

Thank you very much for your involvement. I will do what you indicated and I will keep you informed.

Cabin fuse 5, 7.5 Amp rated, seems to be the origin of rail A20.

2 hours ago, Breezy_Pete said:

Cabin fuse 5, 7.5 Amp rated, seems to be the origin of rail A20.

 

I am so glad that I fixed the car that you cannot imagine.  I wish you and your family all the best in the world and good health.  Thanks again!

The defective clutch position sensor gives an error to the brake switch.  In the case of my car, both were defective.  There is another situation in which the defective throttle gives an error to the ASR.  Opel says exactly where the problem is, not like VAG.

Brake pedal switch  and clutch switch both use that same A20 voltage rail, so if the fuse was blown, that's why they were giving bad info. Oil level/temp sensor also uses it, if your car has such a thing in the sump?

It would be good to work out why that fuse failed.

I have asked myself this question lately.  What could have caused these things.  I've had the car for 6 years and it's never had anything like this.  I can associate only one thing with these problems: a month ago the Blaupunckt cd player could not be started anymore (the start button has those graphite contacts or something like that that have been erased).  I use the player for bluetooth calls while driving long distances.  I couldn't live without a player and I considered two options: either I take the JVC from my wife's Opel and put it in my Skoda and in its place I get a second-hand original GM CD player, or I get a new player.  I made the mistake of buying a cheap, chinese, new player with Bluetooth function.  In the evening when those errors appeared on board, the player was on.  A quarter of an hour before I noticed some strange characters on his display and I thought, look, it didn't even last two weeks.  I disconnected it and took it out of the board.  I will buy something good, Blaupunkt, Sony.  So it's the only thing recently added to the car.  There were errors in the car with the two clutch and brake sensors, the fans and the throttle.  Now the car works flawlessly, without errors.