P0638 Throttle Sensor....Stalling

[XXXArlow]

Hello, I posted a few weeks back regarding my 2004 2.2 DTi stalling with warning light.

Cutting a long story shorter, I took it in to the Ely Dealer and they came up with a few fault codes but were not very helpfull diagnosing the actual problem. "We can keep it, but itll cost you £75 an hour"

* Mass Air flow
* Throttle Sensor
* Vacuum Sensor
* Possible ECU malfunction

I've changed the Mass Air Flow and repaired 2 split boast pipes.

Because of the entirely un-helpfull nature of the Mechanic I have purchased an Op-com unit and this morning after repairing the the 2 pipes I had no errors and thought I'd sorted it all out.

I managed to do 50 miles on a near empty tank, but as soon as I filled it to the top with Diesel the problem came very quickly back and happend 10 times on the 15 miles home.

I had my Laptop with me and every time it happened it came up with -

OP-COM 070209 - PC based diagnostic tool

Control Unit:
Part Number: 55350002_ SH
Vehicle VIN:W0L0ZCF3541032385
Identifier:0x0416

Total number of fault codes: 1

P0638 - Electronic Throttle Sensor Circuit High Input
(07) - Present


I know this is quite clearly a problem with the Throttle, but I am a little confused why a heavy tank would bring this error up so quickly??

The mechanic at the Dealer mentioned fitting a new Throttle Position Sensor (he even gave me the part number), but before I go spend £120, I wanted to hear some 2nd opinions.

Thanks in Advance

Andy

(BTW I'm in Newmarket if anyone ever asks for some help with Fault code diagnostics)

[XXXArlow]

Any help from the evening browsers?

[sb1uk]

Hi if you need a throttle pedal I have one for a manual car. £60 done 44k.

[fattony]

you could try a breakers yard before splashing out

[XXXArlow]

Thanks for your replies.

I have a 6 month Warranty on it, but need to be 100% clear on the fault before making a claim. I've been told that I would have to repay the payment if it turns out the repair hadn't fix the problem.

Now that I have the Fault code I'm nearly there, just wanted to know if the Sensor would play up under weight strain or if it could be something else.


Does anybody know if the Throttle sensor can be effected by anything else or if its a clear error?

E.g. Boost sensor can be effected by split hoses

[benny]

it needs a new throtle body comon on these engines the sensor dont know where the buterfly is and closes it wich makes the engine stall ...

[XXXArlow]

I have been googling this all night and just found this article from www.aa1car.com :-

THROTTLE-BY-WIRE DIAGNOSTICS
Most of the faults that occurr in a Throttle-By-Wire control systems are things you would expect, like pedal or throttle position sensors that wear out and skip or produce erratic signals, motor failures in the throttle body, and electrical problems like loose or corroded wiring connectors.
A code reader or scan tool is required for diagnostics. Generic OBD II trouble codes for possible pedal position sensor faults include P0120 through P0124, P0220 through P0229, plus any OEM enhanced P1 or P2 series codes for that specific vehicle.
If a fault occurs in the motor on the throttle body, it will be detected by the feedback signals from the throttle position sensors. Generic OBD II codes for this kind of problem include P0638 & P0639, plus any OEM enhanced P1 or P2 series codes for that specific vehicle.
The Throttle-By-Wire system also monitors the throttle position sensors on the throttle body. A fault here may set any of the same OBD II codes just listed for the pedal position sensor, or OEM enhanced P1 or P2 series codes for that specific vehicle.
Diagnosis involves reading the fault code(s) to determine the circuit that is experiencing the problem, then checking the voltage or resistance of the pedal or throttle position sensors with a DVOM, or checking the operation of the throttle control motor (visual observation of the throttle when the motor is commanded to move, and/or checking the duty cycle commanded by the control module using a scan tool).
When the fault has been identified, the faulty part can then be replaced. The codes can then be cleared, and hopefully everything will work correctly again.


Going to book it back into dealer tomorrow and hopefully they can be a bit more helpfull now that I've found the Fault code.

Wish me luck

[C9_hardlatch]

My 53 Signum 20Dti went in with that fault code. Receipt says its "throttle control neg deviation" Symptoms were a sort of hesitation at about 2000 revs and when stopped at a junction etc and idling, when you put your foot down to move off..nothing happened...foot flat to the floor and shes just idling!!. Garage did vac pipe check and cleaned out the throttle body which apparently was full of gunk. Car much improved after that. How ever they did if it reoccured that it may require intake manifold removing and cleaning and or air flow meter replacing. Sadly the fault is back..so when the weather is a little better, going to clean the intake manifold and the egr valve as well.


HTH

Neil

[XXXArlow]

Hello C9,

I've already cleaned out the EGR valve and replaced the Mass Air flow with no luck

My cars actually just stopping whilst driving. The Warning light come on with no acceleration and then cuts out when coming near the stop.

Apart from that its running well....


The site I found is pretty in-depth with its articles. The link on my previous post for the Throttle sensor explains it quite well:-

DRIVABILITY SYMPTOMS
The classic symptom of a defective or misadjusted TPS is hesitation or stumble during acceleration (in other words, the same symptoms a bad accelerator pump would produce). The fuel mixture leans out because the computer doesn't receive the right signal telling it to add fuel as the throttle opens. The oxygen sensor feedback circuit will eventually provide the necessary information, but not quickly enough to prevent the engine from stumbling.
Throttle position sensors typically experience the most wear in the position just above idle, since this is the throttle's position for most driving. A worn sensor may cause a skip or drop in the reading when the throttle opens, causing a momentary loss of input to the PCM. The result is usually a hesitation or stumble because the PCM fails to provide the necessary fuel enrichment.
If the TPS mounting is loose, it will produce an erratic signal leading the ECM to believe the throttle is opening and closing. The result can be an unstable idle and intermittent hesitation.
If the TPS is shorted, the computer will receive the equivalent of a wide open throttle signal all the time. This will make the fuel mixture run rich and set a fault code that corresponds to a voltage signal that's too high.
If the TPS is open, the computer will think the throttle is closed all the time. The resulting fuel mixture will be too lean and a fault code that corresponds to a voltage signal that's too low will be set.


Hopefully now the Mechanic can pay some close attention to either the sensor or the body.

[XXXArlow]

Cars now at the Dealers ready for a £70 test drive GRRRRRRrrrrr.

They really aren't very helpful. However much I asked him for advice or to actually check the throttle area, all he could reply was -

"If the faults not present, we cant help you"

Will keep this post updated.