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Help with fault codes p0638, p0500, p0402


TheBrowns

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Hi everyone, I hope your all as well as can be.

It’s been a couple years since I needed to ask a question so hope someone can help.

As most our vans (Own design built by Nu Venture 2011 Ducato 2.2 120. With 56000 miles) it hasn’t been used much in last 14 months but has had a few good runs.

Yesterday drove approx 250 miles over half at 70 on motorway everything absolutely fine and pulled as should with excellent response.

 

Van woke up this morning and was very sluggish almost as if turbo not coming in, I.e Not much power.

After various hours and stops etc (as pooteling around Northumberland) the engine management light came on.

 

I have read the following fault codes p0638, p0500, p0402. I cleared the codes and gave the van a run but whilst engine light not back on the problem is still there, very little power.

 

Obviously I looked up codes. But has anyone anything sensible to offer that I can physically look for or is it a job for a mechanic.

 

Best Regards Graham.

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The fault is with the throttle body , P0638, with a knock on effect on the EGR valve, P0402. P0500 is a speed sensor that I would disregard for now.

You need to clarify which engine you have. Some Fiat Ducato were fitted with the 2.2 Ford Puma engine but most have the IVECO 2.3.

I suspect its the IVECO 2.3 engine in your van.

There are three parts to the exhaust gas re circulation system, the throttle body, the pressure converter, and the EGR valve itself. The throttle body acts as a kind of diverter valve for air flow into the engine, the EGR valve allows a certain amount of exhaust gas to flow to the throttle body, and the pressure converter, driven by the ECU directs a vacuum to actuate the EGR valve.

 

The most probable cause is failure of the motor in the throttle body requiring complete replacement of the unit. A possible but moderately difficult DIY task. The pressure converter mounted centrally just under the scuttle plastic may have failed or the vacuum hoses become disconnected. You could check this and any electrical connections to the pressure converter and throttle body. It is often necessary to replace this along with the throttle body. The EGR valve is more reliable and rarely fails.

 

If the vehicle is fitted with the Ford 2.2 engine then its a more straight forward repair with replacement of the single component in the re circulation system, the EGR valve itself.

 

The throttle body has been discussed at length in the past so I expect links to previous discussions to be posted.

 

Mike

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Thanks for the replies, it appears as mentioned I have the Iveco engine as there is a large sticker on side of one part and here I was thinking I had a Fiat engine.

 

I’ve checked the F11 fuse and it’s ok.

I’ve taken the valve off from just under scuttle on metal plate. It has 2 pin connector. When engine running on RHS I have 14.8 volts to earth but between pins I have 2.4v

 

Resistance to earth from LHS pin is 42 k ohms

Pipes were on very tight but one has slight split on end now I’ve taken it off.

 

Does this seam correct?

 

Is it possible to take it apart And clean/fix anything or do I just replace it. (Big issue it’s bank holiday and I’m sat 200miles from home in a field in Northumberland ) ??

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The problem is most likely the throttle body not the pressure converter valve. As a workaround remove the RH pipe from the pressure valve. This will prevent the EGR from opening and may restore some engine performance as a temporary measure.

 

If the throttle body has never been changed for the later type it may/will have failed. A crude test to determine if the throttle body is faulty is to remove the large diameter tube from the inter cooler and attempt to move the throttle plate. It should move freely and return to the rest position.

 

Access to the throttle body is difficult and the slam panel and plastic grill assembly needs to be removed for easy access, The picture shows a new body with the tube from the inter cooler entering on the left.

 

Mike

544237756_throttlebody.jpg.8ca5e3634086d83f97ec8f97d775079f.jpg

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Thanks Mike, just got back after a day out (slowly). I’ve removed the pipe from intercooler and the throttle plate does move freely.

I will try removing the RH pipe from pressure valve and giving a run later today. I’ll let you know how I get on.

 

P.s nothing has been changed on van as we’ve had it from new.

 

The van was made just in the change to newer engine. I got older engine but new black dashboard!!

 

Thanks Graham

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If you have the black dash then it should be the later, more reliable, throttle valve. Comprehensive diagnostic systems can operate and test actuators. This would save guess work and identify where the problem exists.

 

Mike

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Hi Colin. Thanks but I checked Air Filter first it’s as clean as a whistle only changed 2-3 months ago.

I’ll have wait till back home I think to get it sorted as not many garages around here and don’t want to spend a full day driving and waiting around one for them to say we need to order XY&Z

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