Its probably the speed sensor. a new one is about $80 US. You can test this by scanning your x for codes when it comes on. If it comes back as "right front speed sensor" then swap it with your "left speed sensor" to test it. If the code still comes back as "right front speed sensor" with the differnt sensor then you probably need a new ECU according to the Service Mananger I spoke to.

Are you under warranty? If so the dealer probably tried the cheapest thing possible first. as they dont want to put up $900 for the new ECU.

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2002 4.6is Dinan S2
Titanium Silver/Black Alcantara

DINAN
Stage 4 Engine Software
Automatic Transmission Software
High FlowThrottle Body
Free Flow Exhaust
Cold Air Intake System
High Flow Air Mass Meter
OTHER
CCFL Angel Eyes
Stealth XM Radio in ashtray : FM Mod
Pilot H3 Fog Bulbs
Cleared Headlights: Hi/Lo Beams
Hardwired Radar Detector
IN PROGRESS
Powerstop C/D Rotors: (on backorder)
W/EBC Red Stuff (F)
W/Axxis Deluxe (R)
Dice Ipod: Aux Input for XM
THINKING
SMG II
MK4
Bluetooth