My Yeti ( 2.0 TDI 4X4 ) went into limp mode couple of weeks back. ECU scan displays an error message "Sensor reference voltage B P0651 00 [167] OPEN CIRCUIT". It looks like a wiring issue or sensor problem. Technicians ruled out ECU failure, but  unable to locate the trouble. Any possible solutions ?

Year of manufacture and engine code are handy details to add.

1 hour ago, Wino said:

Year of manufacture and engine code are handy details to add.

Thanks. It is 2013 Model 2.0 TDI 4X4 , 140 Bhp Yeti. Attached VCDS full screen showing the Controller Codes.  Hope this helps.  Please advise.

That may be enough info to work out your engine code, and so find the correct wiring info.

 

This topic gives a list, but slightly out of date, probably CLCB engine code? Does this code appear on a sticker in the car boot, in the service book, or on the cambelt cover?

https://www.briskoda.net/forums/topic/149044-yeti-engine-codes/

 

Sorry, can't find anything that obviously corresponds with "Sensor reference voltage B" in the wiring information.

Only thing I could guess at is that it's a 5V reference from the engine ECU going to various sensors/actuators including the throttle valve (pin 1, yellow/blue wire) so maybe check if that is present and correct if you have a multimeter.

It seems to start from pin 25 of a 60-way connector of the engine ECU.

 

But... if that is sensor reference voltage B, I'm not sure what sensor reference voltage A might be, so probably not very useful info, I'm afraid.

Surely the first thing to find out is which sensor is given a false/incorrect reading?
Is that 4124?

All yours Shirley.

1 hour ago, Llanigraham said:

Surely the first thing to find out is which sensor is given a false/incorrect reading?
Is that 4124?

Thanks for the responses.  That is exactly what I am looking for. Is there a reference document to look for the sensor code ?  I understand that particular sensor should be a NC contact that is kept OPEN at the moment, which prevents the turbo from turning ON. It could be a faulty sensor, or a broken wire going to that sensor.  If I pull out  sensor cables one by one and scan every time, it should give an error corresponding to that specific sensor I isolated.  By this trial and error method, I may be able to find out the faulty sensor, but it is a tedious job.  I happened to read somewhere that this error could be from 'Throttle Body Sensor' or 'EGR Valve'. Hope someone knows how to pinpoint the device from that error code.  

Edited 21 October, 20187 yr by GOPAN

I think that reference voltage will be used by more than one sensor, and that fault code is not - as far as I can see - telling you anything about which ones are involved.

Test the +5V at the one I suggested, if it is reasonably easy to access and back-probe while ignition is switched on or engine running.

 

26 minutes ago, GOPAN said:

I understand that particular sensor should be a NC contact that is kept OPEN at the moment

I don't think this is true. I think here  'Open' just means that some sensors are behaving as if their +5V is not present.  It's not clear to me why there are not also sensor-specific fault codes for the affected sensors.

 

Were the 'Technicians' you mention in your first post at a Skoda Dealership?

 

1 minute ago, Wino said:

I think that reference voltage will be used by more than one sensor, and that fault code is not - as far as I can see - telling you anything about which ones are involved.

Test the +5V at the one I suggested, if it is reasonably easy to access and back-probe while ignition is switched on or engine running.

 

I don't think this is true. I think here  'Open' just means that some sensors are behaving as if their +5V is not present.  It's not clear to me why there are not also sensor-specific fault codes for the affected sensors.

 

Were the 'Technicians' you mention in your first post at a Skoda Dealership?

 

Yes. The car is still in limping mode. Currently being attended by a Skoda service centre.  Today is Sunday. So, we'll try these points tomorrow.

Update on the issue.  The failed component was identified as Boost Pressure Sensor. Replaced and problem solved. 

Thanks for letting us know what fixed it. Could be very useful to others who see the same fault code in future.

From what I can see, that sensor (charge/boost pressure, G31) doesn't share any wiring with any others, except it's earth, which is shared with the intake air temperature sender (G42) which is combined in the same 4-pin package. All four wires go to engine ECU and nowhere else.