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Turbo boost sensor failure again - Repeated fault code p0238


tringy

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have a 2015 2.3 150 x290 maxi ducato motorhome with a continued problem of code p0238 - A circuit high. On previous advice from the original AA breakdown and the error code read at the time the sensor was changed. I have now changed this sensor twice, both times it lasted approximately two to three thousand miles, then I get the same problem eml limp mode and on reading the code with my Autel reader the error P0238 circuit A high appears. This always seems to happen when I have been driving two or three miles from cold and under load uphill. When this happens I stop and delete the code and all is ok maybe for 3 or 4 hundred miles. 
Any suggestions on how I can fix this problem? I don’t really want to throw money at Fiat dealers because I have no confidence in them from past experience. 
Can anyone offer further advice on this problem please. 
thank you  

David Tring

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  • Derek Uzzell changed the title to Turbo boost sensor failure again - Repeated fault code p0238

It could be worth replacing the engine/gearbox to body earth cable (or adding another) which can look ok but have been known to have a fault (resistance ? ) causing odd  electrical  sensor faults

Edited by Labby
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Thanks for the advice given from both Keith and Derek , I have sent an email to ask for advice from mmmtech and hopefully nick fisher may respond. 
Some years ago I had great advice about a different issue on my previous motorhome from nick and he saved me a lot of grief and money. What a TOP chap. 
Regards.Tringy. 
Dave Tring.👍🤞

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Hi 

What other codes is your reader showing Have you had  a professional diagnostic done? If so what was their advice (not just AA)  It may be prudent to first check and ensure all earths as advised (by Labby) are in good condition as also your wiring loom to your ECU for damage and loom from sensors to the ECU and associate earths for damage

Regards

Edited by onecal
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Fiat had a bad batch of earth cables around 2008. 

At least the few I have heard of relate to that period

So I doubt if they were still fitting them in 2015?

And a duff earth connection wouldn't explain why a new sensor fixes it for (quote) 'approximately two to three thousand miles'

Sounds to me more like a bad batch of sensors than another bad batch of earth cables

As we have seen from another thread, https://forums.outandaboutlive.co.uk/topic/65161-engine-oil-approvals/#comments Personally, I would rather take it to a diagnostics centre than a general repairer.

Its likely they would tell you a lot more than an autel code reader

I binned my autel code reader because it never told me about a faulty soot sensor that was revealed by the free google car scanner app on my chromebook.  (maybe because the google app gets updates?) 

Incidentally Soot sensor can be replaced easily but it was under warranty so I got it done at the dealer and they said faulty soot sensors is a known issue.  I understand there are over 150 sensors on my Ducato Euro 6 so a lot to go wrong.

Edited by John52
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13 hours ago, onecal said:

check and ensure all earths as advised (by Labby) are in good condition as also your wiring loom to your ECU for damage and loom from sensors to the ECU and associate earths for damage

If that was the problem why would a new sensor fix it for 'two to three thousand miles' - twice?

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I have been given a some things to inspect by nick fisher and possibly some replacement parts I will report back with an update but it won’t be for sometime as I have other commitments that must come first. Thanks for all your support,much appreciated. Regards Tringy.

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In answering John's question as I have found many a time Tech's sometimes replace the sensor/sensors and do not do a simple wiring loom test to check from ECU pins to sensor pins and all connection blocks. The movement on replacing the sensor sometimes allows a timeframe before the said wiring gives trouble again . Earths should always be checked as also reference voltage . This indeed may not be your issue but it's the first path you should check and with the least cost to you .Have a good diagnostic Tech' check done by a known good Tech' first to narrow down what really may be causing your issue and taking out a lot of guesswork  and can go a long way in solving your problem before just replacing parts as you have done in the past as you say (sensors) 

Good rule of thumb  First find the issue ,  then repair it or replace it

Regards

4 hours ago, John52 said:

If that was the problem why would a new sensor fix it for 'two to three thousand miles' - twice?

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1 hour ago, onecal said:

 a simple wiring loom test to check from ECU pins to sensor pins and all connection blocks. ...Earths should always be checked as also reference voltage .

Can you describe your 'simple wiring loom test

- that checks all that lot, and all the earth connections, for intermittent faults?

Edited by John52
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Hi John

Without coming as across as being rude , if you don't know how to do that you should leave well enough alone . For that very reason it should really be left to those that know what they are doing A good known reliable Tech' .Of course you can also without any diagnostic equipment just wiggle the wiring , sometimes it can have the effect masking the fault in the loom for awhile Lets see how the OP gets on and hopefully have the issue resolved without incurring as he says himself a lot of grief and money  

Kind regards

4 hours ago, onecal said:

In answering John's question as I have found many a time Tech's sometimes replace the sensor/sensors and do not do a simple wiring loom test to check from ECU pins to sensor pins and all connection blocks. The movement on replacing the sensor sometimes allows a timeframe before the said wiring gives trouble again . Earths should always be checked as also reference voltage . This indeed may not be your issue but it's the first path you should check and with the least cost to you .Have a good diagnostic Tech' check done by a known good Tech' first to narrow down what really may be causing your issue and taking out a lot of guesswork  and can go a long way in solving your problem before just replacing parts as you have done in the past as you say (sensors) 

Good rule of thumb  First find the issue ,  then repair it or replace it

Regards

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5 hours ago, John52 said:

Can you describe your 'simple wiring loom test

- that checks all that lot, and all the earth connections, for intermittent faults?

I'll take that as a 'no' then?

Why did you suggest it if you can't say how to do it?

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4 hours ago, onecal said:

if you don't know how to do that

I could do all those things manually but it would be hugely time consuming, and still might not show up poor connections.  Just consider all the connections and wiring you are including, and how inaccessible it is!!!!!

Thats why I  was hoping you could enlighten us all as to your 'simple' method to do all that.

Which you think would be more practical than just fitting a new sensor and getting it going.

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