Symptoms
High idle on start-up (1,100–2,000 rpm), hunting idle, or idle that won't drop despite the ECU asking for about 700 rpm.
The fix, step by step
- Rule out vacuum leaks, then watch the valve with RoverGauge, which can read the 14CUX and command the stepper open and closed.
- Clamping the bypass hose is a quick test.
- One owner replaced the IACV, temperature sensor and plenum gaskets before finding the new aftermarket IACV itself was faulty; a second replacement fixed it.
Tools & part numbers
- RoverGauge and cable, hose clamp, multimeter
- idle air control valve, plenum gaskets as needed
Where to buy the parts
ETC6660 fuel injection stepper motor, V8 EFI, Discovery 1 / RRCLR Direct ↗Amazon ↗
Stepper motor gasket, EFI V8, Discovery 1 / RRCLR Direct ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Land Rover Discovery Series I parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.