Additionally, as I understand the system reads differences in resistance. A US vs OEM bulb will measure differently. Replacement in pairs may help.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Corrosion also can cause a lower than spec measurement.....check for any dimmer lights and run a piece of fine sandpaper over the connectors....mine was acting up and it was a slightly corroded bulb socket....took me forever to find!