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Matt, Mechanical Engineer
Category: Ford
Satisfied Customers: 22932
Experience:  BEng hons Mech engineering, in auto industry 22 years
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P0335 fault code = crankshaft position sensor A circuit. Have

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P0335 fault code = crankshaft position sensor A circuit. Have replaced sensor, for sake of & cheap cost, but old one seems ok in comparison (resistance reading up to spec. & same as new) Other features are at start-up, ie. turn ignition on, wait for all the usual warning lights to go off, start engine ok, taco normal, but then; ABS light momentarily comes back on and then goes off with taco dropping to zero at same time (and stays there all the time while car is driven) The rpms do still show on the code reader! Overall, the car runs fine/normal, tho' have noticed a very rare momentary 'die' and/or misfire.
Vehicle/engine details: Ford Focus Estate, 55 plate (Jan. 2006 reg.) with 1.6, 16v, Ti-VCT, Duratec petrol engine, having done 101,750 miles
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if you have a faulty crank sensor then usually the engine will struggle to start if its starts at all so that fault code I'd say isn't quite right

so I'd suggest checking over the cam sensor circuit and sensor too as this is used a lot in starting and the engine speed signal

also trace the crank sensor wiring back to the main loom, checking for insulation damage as you go
Customer: replied 3 years ago.

Hi Matt

Thanks for your response. However, as I said, I have replaced the sensor even though I didn't suspect it being faulty.

The engine starts without any problem.

As for checking the wiring, I tried doing that by removing the harness cover from the pcm but, as there are no exposed cores + numerous wires of the same coding/markings, it seems to be an almost impossible task!? There was one which was flattened (presumably by being trapped) so I scraped a finite amount of insulation before and after the flat and managed to get test-meter probes touching the cores to prove that there was no break. At the same time I checked that wire for a circuit to the crank sensor plug, with no result.

But, as I also said initially, using my code reader (on the 'live data' setting) the rpm reading is displaying satisfactorily, so doesn't that confirm the crank sensor circuit to be ok?

I saw a question/answer on the site recently, from a workshop engineer, regarding the facia/display? Not sure if it meant the instrument cluster, but it suggested that there is more too it than just warning lights & gauges, and that it works in conjunction with the pcm and that faults can give false information to the pcm. Am I right and, if so, could there be a fault which could cause my problem, and would give some kind of 'link' between the abs light popping back on/off and the taco then dropping off?

Hoping you can help further, sorry there is a lot to read.

Cheers, Peter

Hello Peter

Ok thanks for the extra information

this is sounding more like faulty instrument cluster then

the only way to diagnose test these is to get them done off the car

this firm can handle this
Customer: replied 3 years ago.

cheers ***** ***** hoping I was on the right lines.


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Customer: replied 3 years ago.

Hi Matt.

Well, my problem is becoming a right mysterious saga!!

I haven't had an opportunity to go any further, as the car has been in use.

However, when I started it yesterday the taco kept going!

In addition, contrary to me believing that the engine had previously been running normally, it must have been running in 'limp mode' as this time it was off 'like a rocket'. Can only assume that the faster 'cold' tick-over & subsequent easy drive away misled me. Thought 'limp mode' would have been more evident.

So cleared the fault codes & seemed ok, though haven't had a long run since.

I must add that after start-up the ABS light still pops on & then off again, as before. But, is it correct that the basic hand-held fault code reader doesn't pick up faults on the ABS system?

Also, with regard to the rpm reading on the code reader 'live data', is it true that it can be picked up from the CAM sensor? Mine has two.

Well, that's the situation at the moment, but, any explanation please?

What could have caused the problem TEMPORARILY, so that I can check it out to hopefully avoid it reoccurring??

Here's hoping,



Hello Peter

the Cam sensor will also provide a 'rough' speed signal to the ECU

and if this isn't functioning then the engine won't synchronise its injection timing corerctly

so its quite possible one of the cam sensors is faulty

although this should be picked up by the code reader

and yes you're right the small generic code readers tend to just get the engine faults and body issues like ABS faults tend not to be recognised
Customer: replied 3 years ago.

but what about finding, and rectifying, the original cause? to avoid it reoccurring!


well like I said i think the limp home aspect may well be due to a faulty cam sensor

the failing rev counter though will still need the the instrument pack sending off


do you still need help with this?

Customer: replied 3 years ago.

Yes, I think I might well need some more you know a good exorcist !!!?? 'cos am sure that when I have finished typing this, the 'gremlins' will have found something else to puzzle me, as, amazingly, at this moment, everything is fine!! Though, in the mean-time, I have had a P2303 fault code following intermittent periods of misfire & lumpiness. But, unplugged & removed it to do some testing, refitted, running ok.! However, there is evidence of water in the spark plug 'well' and leaks from screen wash jet pipework.

I have a theory re, original CRANK sensor code & taco zeroing - could it be, as we have said, the instrument cluster may be at fault, which caused the taco problem, and in turn, THIS gave the pcm a false indication of the crank sensor being at fault.

There is still no actual evidence to suggest cam sensor(s)

All in all, I think you will agree, this has been quite a saga of mysterious & unproven events which have had no conclusive outcomes, and, therefore, don't think can really be taken any further. Unless you have any more to add?

Hello Peter

well thats a tangled web for sure,

I'd agree that apart from fixing the screenwash leaks and cleaning out the spark plug 'wells' there's not much more you can do for now
Matt, Mechanical Engineer
Category: Ford
Satisfied Customers: 22932
Experience: BEng hons Mech engineering, in auto industry 22 years
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