Hi, 

 

I have a Mk2 2011 Skoda Octavia Scout 2.0Tdi 4x4 for around 10 months. Its had a few issues previously with the P0651 (Sensor Reference Voltage B Circuit Open) code which resulted in the replacement (carried out by myself) of the following:

 

Throttle body unit (calibrated after install)

Throttle pedal

High Pressure fuel sensor

 

The issue I have right now started from hitting a pothole, I was shown the flashing glowplug lamp and then put into limp mode. I pulled over and scanned the code which was a P0651. As I have had this code read out before, I went to the throttle body and unplugged it and the P0651 code went away - this resulted in the following codes appearing:

 

P0193 - Fuel Rail Pressure Sensor 'A' Circuit - High Input

P0405 - EGR Sensor 'A' Circuit Low

P2127 - Throttle/Pedal Pos Sen/Switch E Circuit Low Input

P2100 - Throttle Actuator Control Motor Circuit Open

P0123 - Throttle/Pedal Pos Sen/Switch A Circuit High

P2563 - Turbocharger Boost Control Pos Sen Circuit Range/Performance

 

I have gone into the process of testing for input voltages, grounds and Resistance amongst the wires. I have inspected the plugs for the Fuel Rail Pressure Sensor, Throttle Body & Turbo Boost Control Solenoid as they are the easiest to access.

 

I am now currently thinking this may be an ECU Malfunction, I will be jacking the car up and accessing the EGR plug to check its values in the coming days.

 

I should also add, when i plug the throttle body back in, all of the 6 codes listed above disappear and the P0651 returns. Any one have any ideas to what may be causing this or what next plan of action to take?

 

Thanks in Advance.

I know nothing other than some basics which I always start from.

 

Is the scan tool you are using appropriate to VW programs and at an appropriate level, and specifically to your model and year (or VIN) of car and is it fully updated with all program updates for your model and year (or VIN) of car, if not accuracy of some readings/codes can be suspect.

 

Your car is about 13 years old so odds things can happen and show up (flashing glow plug lamp)(?)).

 

Have you seen the following, perhaps you could get help there too. - https://www.obd-codes.com/p0651

 

The fact that you current issue started when you hit a pothole might be significant, or of course might be a coincidence), you have done some testing and you may have already also done the following, did you check the condition inside and out of all connectors, cleaned and repaired if required, condition of wires and checked connectors and wires are secure and protected, tried wiggle tests whilst the engine is running (on the ones you mention and others).

 

Also consider that you might have more than one issue at once or that more than one thing might be contributing or combining to one or more issues.

 

Always, test any testing equipment before making tests to confirm accuracy and double-checked things you have previously checked even if you think you've checked them enough or "it wont be that".  Another set of eyes, ears, nose, touch, hands, mind on site can often be useful to confirm things or Sod's Law find what you've missed or previously checked.

 

That's me out of ideas.  Good luck.

 

6 hours ago, nta16 said:

I know nothing other than some basics which I always start from.

 

Is the scan tool you are using appropriate to VW programs and at an appropriate level, and specifically to your model and year (or VIN) of car and is it fully updated with all program updates for your model and year (or VIN) of car, if not accuracy of some readings/codes can be suspect.

 

Your car is about 13 years old so odds things can happen and show up (flashing glow plug lamp)(?)).

 

Have you seen the following, perhaps you could get help there too. - https://www.obd-codes.com/p0651

 

The fact that you current issue started when you hit a pothole might be significant, or of course might be a coincidence), you have done some testing and you may have already also done the following, did you check the condition inside and out of all connectors, cleaned and repaired if required, condition of wires and checked connectors and wires are secure and protected, tried wiggle tests whilst the engine is running (on the ones you mention and others).

 

Also consider that you might have more than one issue at once or that more than one thing might be contributing or combining to one or more issues.

 

Always, test any testing equipment before making tests to confirm accuracy and double-checked things you have previously checked even if you think you've checked them enough or "it wont be that".  Another set of eyes, ears, nose, touch, hands, mind on site can often be useful to confirm things or Sod's Law find what you've missed or previously checked.

 

That's me out of ideas.  Good luck.

 

Thanks for the advice and your own input. 
 

I tried the following:

my machine (TopDon Artidiag) and the works Snap-On Solus and Autel MK808BT and all show the same codes. I have a friend who lives 3hrs away coming up Sunday who has VCDS -which may show a lot more data at time of fault.

 

I have checked all but the EGR Plug as it’s difficult to reach. I have heard these can fill with water and corrode so I will try check this tonight. I had the back of the ECU last night checking connectors for water damage and checking pins for play. 
 

As I said another pair of hands coming on Sunday to show some light to the situation hopefully. Failing this I will be sending it to an Auto Electrician. 
 

Thanks for the input, really helps me to have someone else’s input to get the cogs running 😂

 

 

All three scanner could have program holes and glitches and without knowing who owns them they might bot be fully up to date so hopefully an appropriate VCDS machine might show more or different.

 

Live data with everything plugged in may give leads, error codes aren't always the be-all and can even sometimes be misleading or distraction(s) and diagnostics done without error codes (or even a scanner sometimes).

 

Have a look at that link I put in my last post and see how you get on Sunday, best of luck.  If you have to get an auto-electrician in make sure his scanner (if only their were more women working in the car trade) is appropriate  to your model and year (or VIN) of car and is it fully updated with all program updates for your model and year (or VIN) of car.  I've not dealt with auto-electricians but I have other sorts of electricians and in my personal/business experience many of them can be lazy and looking for shortcuts and don't always have their tools fully ready for use.

 

Had an afternoon of double checking and triple checking everything. VCDS showed nothing that we didn’t already know. All wires intact and solid.
 

We replaced the Fuel Rail Pressure Sensor which was showing - High input (Short to B+). We tested the internal resistance of the sensor between the signal and 5V+ which showed 0.6ohms whereas the new sensor showed 1ohms. Once the sensor was replaced the Fuel Rail Pressure Sensor the P0193 code cleared. As has the P2100 and P0123’s with a new throttle body. 
 

It seems that most of the sensors on this A circuit have been shorted to 12V+ in a scenario where no wires have rubbed through. 
 

I have bit the bullet and sent the ECU away for analysis and repair (if needed) in hopes that the ECU has faulted and caused this short. In any event I can see myself having to replace the electronic actuator on the turbo and the EGR. 
 

I will post an update once I find out about the condition of the ECU.

12 hours ago, Conscisior said:

It seems that most of the sensors on this A circuit have been shorted to 12V+ in a scenario where no wires have rubbed through. 

A short to 12V fault code can also mean that a wire (or corroded connector pin) is open circuit.

 

You say you've checked the wires are intact, but have you checked any connectors in the circuit too?

2 hours ago, PetrolDave said:

A short to 12V fault code can also mean that a wire (or corroded connector pin) is open circuit.

 

You say you've checked the wires are intact, but have you checked any connectors in the circuit too?

All the connectors related to the affected sensors and ecu have been checked for corrosion and damage. No issues have been found. We checked this when we were testing the sensors for internal resistance and 5v references to sensors. I have read that EGR’s tend to fill with water but I have had the connector off and used a mirror to inspect the female side and tested the input voltages and signal voltages to/from them.

So I’ve sent the ECU away to get checked and they have determined that nothing is wrong with the ECU. I have since checked the throttle pedal and old fuel rail pressure sensor. Both seem to have less than 1ohm  resistance across the pins. 
 

I don’t have a scooby about what caused these sensors to all fail simultaneously. I’m gutted. It seems I’m going to have to replace the actuators on the turbo and egr and the throttle pedal. It’s seeming likely I’ll be fixing these, replacing the timing belt and water pump and selling her . 

Sad that you will have to do such much work and parts to be able to sell but sometimes you are best to cut your losses and get shot, on the up side you've only had 11 months of suffering and it could be more and for longer.

 

Good luck.  BTW, I have seen again, right or wrong, that Snap-On scanners tend to be less reliable, but then all have there faults, computer programs are all.

 

 

Good luck.