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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22741
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 1999 mk4 golf 1.6 8v when the engine is cold it

Customer Question

I have a 1999 mk4 golf 1.6 8v
when the engine is cold it idles anywhere between 1200 and 4000rpm but once it heats up the idle returns to normal around 800rpm.
Getting fault code 00533 throttle position sensor idle control lower limit
Submitted: 4 years ago.
Category: Car
Expert:  Matt replied 4 years ago.

this does really sound like an vacuum leak to me and the best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

however the fault code makes me think that there may be an issue with the wiring loom to the throttle body - as you've already replaced the body
Customer: replied 4 years ago.

How do I go about checking the wiring loom to the throttle body.

Expert:  Matt replied 4 years ago.

Hello Ashley

1st just do a visual check checking for insulation damage then disconnect any plugs and check for corroded pins / contacts
if that all seems OK then its time to measure the resistance between the throttle body plug and the ECU plug
Expert:  Matt replied 4 years ago.

do you still need help on this one?