Help P0638 error code

[Rockcrawler]

Had the engine management Light come up as we started the our motorhome to come home last weekend, luckily we were not too from home. Had a mate scan it and it came up with P0638 code we cleared it but after a few minutes it came back on again.
Just changed the throttle control body as it was pointing to that.
Annoyingly the engine management light is still on and strangely the scanner says “ fault cleared but is still present “
It’s just weird that we could clear the fault code so the light went off even though it came back on a few minutes later but now it’s just on continuously.
Any ideas ?

 

[Rockcrawler]

 

[bertiebasset]

I had the same problem. Informed to take it out and "thrash" it,, Took it up the motorway doing 60 in 4th for about 10 miles then up and down the gearbox to keep the revs high. Stopped at campsite for week. Light off when restarted to come home. Still off.

 

[Rockcrawler]

I can try that but it won’t rev past 3500rpm

 

[bertiebasset]

I can try that but it won’t rev past 3500rpm

I normally run in 6th at around 2000 revs so I really upped that to alot higher for the run. I now use the revs alot more to clear out the tubes.

^{_{Subscribers  do not see these advertisements}}

 

[Rockcrawler]

I normally run in 6th at around 2000 revs so I really upped that to alot higher for the run. I now use the revs alot more to clear out the tubes.

I think most of us are guilty of that as we are never really racing to get anywhere when we take the motorhomes away

 

[pappajohn]

OBD code may point to throttle body but it can be anything in the intake system.
Something like a flow sensor will bring up the same code.
To pinpoint the fault needs a professional scanner, not a generic one.
I had a fault on ABS and code said sensor fault.
It turned out the tone ring in the hub, which interacts with the sensor, had broken up and disappeared.

 

[Rockcrawler]

OBD code may point to throttle body but it can be anything in the intake system.
Something like a flow sensor will bring up the same code.
To pinpoint the fault needs a professional scanner, not a generic one.
I had a fault on ABS and code said sensor fault.
It turned out the tone ring in the hub, which interacts with the sensor, had broken up and disappeared.

I totally agree, that’s the thing with scanners they only point you in the general direction. It isn’t even a cheap scanner my mate has got it’s a £2500 Launch. We were able to do a few live data tests but we are still scratching our heads

 

[Landy Andy]

What age is the van? Adblue version?

 

[Rockcrawler]

What age is the van? Adblue version?

Fiat Ducato 160 multi jet 2007 3.0JTD

^{_{Subscribers  do not see these advertisements}}

 

[Guigsy]

The early x250 vans did have issues with throttle bodies failing. Mostly due to water ingress. Mine included. I had the wiring harness updated too (different connectors) to support the new style throttle body.

I also had an issue with the Mass Air Flow sensor which gave similar issues. I replaced it. But at the same time I also found that the connector had been damaged (maybe when they did the TB) so it wasn't staying clipped in. A cable tie clip trick fixed it, but I could have just sliced in a new pigtail.

 

[Landy Andy]

Do you still have light on, and only reving to 3500?

The throttle body and EGR systems are connected physically and via electronics, so a problem with one can cause issues with other.

 

[Rockcrawler]

Do you still have light on, and only reving to 3500?

The throttle body and EGR systems are connected physically and via electronics, so a problem with one can cause issues with other.

Yes Andy the fault code was originally clearing but reappeared after a few minutes but now it won’t clear at all. All we have done is fit a brand new genuine throttle body.

 

[Rockcrawler]

If I put my foot flat down on the throttle it’s revs to 3500 then drops to 3250 and stays there

 

[Landy Andy]

I assume you fitted the newer version of TB (Magneti Marelli) and also the small loom extension?
You can physically check if it is working by removing the intercooler hose where it attaches to it and notice that it should close on engine shut off and then reopen after 1 minuet. The TB only operates for two things. One is on shut down of engine to smooth out, and the other is to force the EGR system to work. Also you can rev engine once it’s warm and upon coming off the accelerator the TB should close, for 1 minuet.

Are you getting any noise or vibration from the vacuum solenoid?
This is mounted on the back of the bracket at mid point under the windscreen.

^{_{Subscribers  do not see these advertisements}}

 

[Rockcrawler]

I assume you fitted the newer version of TB (Magneti Marelli) and also the small loom extension?
You can physically check if it is working by removing the intercooler hose where it attaches to it and notice that it should close on engine shut off and then reopen after 1 minuet. The TB only operates for two things. One is on shut down of engine to smooth out, and the other is to force the EGR system to work. Also you can rev engine once it’s warm and upon coming off the accelerator the TB should close, for 1 minuet.

Are you getting any noise or vibration from the vacuum solenoid?
This is mounted on the back of the bracket at mid point under the windscreen.

The one I fitted was the Pierburg one it came with the small loom extension already fitted

 

[Rockcrawler]

I assume you fitted the newer version of TB (Magneti Marelli) and also the small loom extension?
You can physically check if it is working by removing the intercooler hose where it attaches to it and notice that it should close on engine shut off and then reopen after 1 minuet. The TB only operates for two things. One is on shut down of engine to smooth out, and the other is to force the EGR system to work. Also you can rev engine once it’s warm and upon coming off the accelerator the TB should close, for 1 minuet.

Are you getting any noise or vibration from the vacuum solenoid?
This is mounted on the back of the bracket at mid point under the windscreen.

I will check if it’s opening and closing and will also check the vacuum solenoid. Thanks Andy

 

[Rockcrawler]

All sorted
When I fitted the new throttle body it came with a short wiring harness already connected to the TB which then just plug into the existing plug.
It turns out the short harness had been incorrectly wired ie. ( Friday afternoon job )
Had a diagnostic guy come out who found the problem.
Im just glad it’s fixed
Thank you to everyone that replied and a special thank you to Landy Andy who is was bombarding with questions

 

[Elsie2010]

Had the engine management Light come up as we started the our motorhome to come home last weekend, luckily we were not too from home. Had a mate scan it and it came up with P0638 code we cleared it but after a few minutes it came back on again.
Just changed the throttle control body as it was pointing to that.
Annoyingly the engine management light is still on and strangely the scanner says “ fault cleared but is still present “
It’s just weird that we could clear the fault code so the light went off even though it came back on a few minutes later but now it’s just on continuously.
Any ideas ?

 

[Landy Andy]

All sorted
When I fitted the new throttle body it came with a short wiring harness already connected to the TB which then just plug into the existing plug.
It turns out the short harness had been incorrectly wired ie. ( Friday afternoon job )
Had a diagnostic guy come out who found the problem.
Im just glad it’s fixed
Thank you to everyone that replied and a special thank you to Landy Andy who is was bombarding with questions

That is a great result, and not a problem many would find. I’m sure you are very relieved to have it sorted.

^{_{Subscribers  do not see these advertisements}}