Technical P0638 Throttle Actuator Control Range

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Technical P0638 Throttle Actuator Control Range

AlanRjones

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I have a motorhome built on a 08 reg 160multijet Maxi Chassis which has now covered about 15000 miles. While recently on holiday in Germany the engine emission fault light came on although I felt no other effects. I tried disconnecting the battery but the light persisted and has remained on over the last 1000 miles of my return journey, again with no other symptoms and no change in power or fuel consummption. A local garage has managed to interpret the fault as p0 638 but know no more about it......What does this mean and who should I turn to?
 
Hi Alan
I'm working on one of these (3.0 Diesel) with exactly the same fault. Did you get it sorted, and if so do you know what the cause was?

If not and you're still struggling with this, I'm continuing work on sorting this so will post my findings as I progress ;)
 
Spent some time looking into the P0638 fault today. Used various scan tools with not much more than the basic fault codes & live data.

I used an ELM 327 cable I have, and bought Multiecuscan which although free, the paid version has to be purchased to allow it to work, but it was totally worth it. This allowed me to test the throttle body while watching it. No movement whatsoever. It also listed not just the P0638 fault, but described the way the fault was flagged - in this case short circuit to earth. After stripping off the throttle body from the inlet manifold, then removing the electronic unit from the duct/spindle, water had worked its way into the joint between the two and into the electronic motor. This had swelled up the steel motor body and seized the actuator, also entering the electronics and causing a short circuit. Without the new software the testing would have been much more laborious.

New throttle body on order, will post some pics of the faulty parts and more info after the replacement has been fitted. Hope that helps some of you! Note the throttle body butterfly should spring back to the open position without sticking on a good unit. Any sticking will probably mean the face of the motor/electronics unit has corroded - plenty of water pours over these engines from the scuttle panel, especially if a windscreen has been replaced, as the scuttle sealing is often ignored when the panel is replaced after a new screen is fitted.
 
How did you get on with your Throttle Actuator replacement, Wattoo?
I think I have the same problem, so would appreciate some tips.

G
 
New throttle body (FIAT recon unit) worked for 2000 miles or so, then P0638 returned intermittently. I have checked every conceivable wire to the unit, plus others that link to other items such as oil level control ecu (on bracket for main engine ECU). Tried earthing individual wire to throttle body earth = fault still occurred. Finally ran new feed wire (fused) to battery pos terminal from throttle body. Also fitted inline switch as needs to turn off to prevent battery drain & throttle body having perm feed. (relay would have been better but that would possibly trip the fault code if feed cuts in slower than original supply). So far with loads of road testing, this seems to have cured the fault. Therefore it's looking like something from the main fuse/relay board is causing a supply fault to the throttle body. I've even stripped that down but nothing was faulty on it. If fault returns again I'm thinking engine ECU has possible water ingress - there's a vent in the casing which may let water in. Will report more once more testing done. This is a long winded process
 
Yes I tried with the new loom and also without. It's actually identical to the old connector in terms of connection, just that the new loom simply has a wire missing from one terminal. The original loom has the wire, but it is blanked off in a connector near the main fuseboard.
 
The loom piece was originally supplied by Euro car parts at the time of purchasing the replacement throttle body, was about £15-20 in 2012 if that helps....but they had to be pushed to supply it!
 
Thanks, Watto, for the update.
Good luck with your ongoing investigations.

Following my P0638 code I plucked up the courage to remove the throttle actuator.
I found that water had got into the actuator. It had been running off the engine cover onto the throttle actuator assembly.
I dismantled the actuator, cleaned it up and resealed it.

Replacing the assembly on the engine was rather more difficult than removing it due to the inaccessibility of the front offside securing bolt. Although I did manage to do the job without removing the grill, radiator etc.

Mine is a Peugeot 3L 160HDi, having the same Iveco engine as the 3L Ducato.

The actuator is shown split from the throttle body, prior to cleaning, in the attached photo.

I also managed to separate the actuator stator section from the rotor section and give those a good clean.

Needless to say, I then fitted a plastic deflector, tucked under the engine cover, to divert any water away from the throttle actuator!

Hopefully the problem is now sorted, but time will tell.

G
 

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Hi there,am also having trouble with throttle valve on my Ducato 160 engine.Does anyone have the part numbers for the new throttle and cable so I can order them from Iveco,apparantly 30% cheaper.Many thanks
 
Incredible as I did this last week and only just read your post (y)
The X250 plastic engine cover is on the 3 litre at least inadequate.
If the scuttle hasn't been sealed then any water running onto the cover runs straight off the front directly onto the throttle body electrical connector.
This on mine results in the engine management light coming on frequently with a throttle actuator fault code.
So I've knocked this up as a trial cure.
A dissected 1 litre polythene measuring jug
CA_09271415513157-L.jpg

A 5.5mm hole to accept a pushpin rivet
CA_09271415511949-L.jpg

Fitted
CA_09271415510733-L.jpg

Engine cover replaced
CA_09271415494167-L.jpg

Viewed other way
CA_09271415504044-L.jpg
 
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thanks for all of the info - much it applies to my vehicle. I have been quoted $1500 Australian + freight and installation for this part.

Twice the engine has fired, then refused to rev. Other than that it seems to operate normally.

I have 2 questions:
1. is it possible to successfully remove and clean the internals with replacing the whole part?

2. From the experience of others, how long before the warning light should be dealt with and what is likely to happen?

cheers
:)
 
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To extinguish the warning light with the p0638 warning, start the engine and turn off 6 times in quick succession ... worked on my 08 plate . Fault was the servo in the throttle body ... new modified body and loom .. £350 all in
 
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