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P0608 Diagnostic Code


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Hi there, new to forum. I scrolled through all 31 pages of posted topics and couldn't see this before. Any tips, advice or experience is greatly appreciated. Only symptoms are EML on dash. Nothing else. P0608 code and see pic for description on my code reader. Thanks , Chris   


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47 minutes ago, ChrisFusion1 said:

P0608 code and see pic for description on my code reader.

P0608: Engine control module (ECM), VSS output A -malfunction (VSS = Vehicle Speed Signal)

This seems likely to be an inter-module communications error. Can the code be cleared, & turn the MIL out, & if so, does it re-appear?

If the car has ABS, then the PCM (Ford term for ECM) gets the speed info from the ABS module over the CAN bus (if your car is recent enough to have CAN bus, not sure the 2016 date is valid?)

Forscan, and possibly other advanced diagnostic aids, can read error codes from the ABS & other modules. It can also display & log the wheel sensor outputs.

A major error in the ABS (eg failed wheel sensor) should flag up an ABS error & warning lamp.

It is most likely an intermittent or occasional error corrupting data between pcm & ABS.

I would clear it, & monitor for more errors, (using Forscan to check all modules.)

It does not seem a problem at the moment, but an intermittent comms error on the CAN bus could worsen. But at least then, it would be easier / possible to track down.

One slight possibility is battery voltage dips / surges. If you have a voltmeter, check battery terminal volts do not dip below about 8v when starting, or go above 14.8v when running & charging.


You will find a lot about ELM327 & Forscan on this site, which together provide a very comprehensive diagnosis & maintenance tool. Post here if you want more info.

Note: Simply reading the codes can do no harm, and does not change anything. Just do not reset the codes (and you would have to ask the scanner to do this) if you are going to take the car to a garage.

James (jeebowhite) has done a nice guide: http://www.fordownersclub.com/forums/applications/core/interface/file/attachment.php?id=21196

For an ELM327 adapter, see

you will also need a program called Forscan, its free and you can get it from


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Peter, firstly, thanks for all the information you have mentioned. I have cleared the fault and it appears again, not straight away but after 5-10 of driving. 

I will carry out what you suggested and get my hands on forscan. 

Crazy to say but the fault would be easier to pin point if it was worse!

FYI the car is 2004 90k miles 1.4tdci. 

Thanks again, I will post any further information that I can from the car. 


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