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The purpose of the Idle Stabilser Valve is to control the idle speed to within the specifications of 800 + 30 rpm.

Part Number034 133 455 BBosch 0208 140 512

The picture below displays the ISV and its position in the engine bay at the rear of the inlet manifold.


1.To test the ISV, unplug the connector (1) in the picture above
2.Measure resistance across the terminals on the valve. Must be 7 - 11 ohms
3.If resistance is outside this range, the ISV should be replaced.
4.Re-attach the connector

1.To test activation of the ISV, unplug the connector (1) above
2.Attach a test LED to connector contact 1 of the cable and earth.
3.Operate the starter for a few seconds. The test LED should light when the starter is turning.
4.If the LED does not light,
4.1 check fuse #24,#28
4.2 check connection from contact 1 to fuse #24 for o/c
4.3 check connection from fuse #24 to Fuel pump relay contact 59 for o/c
4.4 check connection from contact 1 to contact 37 of the ECU for o/c.

Inspection / Cleaning

This is best performed by removing the unit as follows:
Unplug the electrical connector.
Remove the bracket (1) from the inlet manifold. This is secured by two small bolts (5mm allen key).
With the bracket loose, slide the holder off the ISV
Undo the clips arrowed 2 & 3 (3 is hidden underneath)
With the clips undone, the ISV should slide off the hoses.

1. Check the rotary slider for signs of rubbing. DO NOT USE A SCREWDRIVER TO MOVE THE SLIDER
2. The valve can be cleaned using carb cleaner. Black carbon deposits should come out the valve when sprayed.
3. When refitting, it is advisable to use new clips if originals are still in place.