Question

2003 Mercury Mountaineer 4.0L how do you fix the code p0406 sensor circuit high?

Answer 1

HI there

This is usually the result of a faulty EGR volume control solenoid or a blocked EGR passage. Here is some more info on the code for you.

P0406 MERCURY - Exhaust Gas Recirculation Sensor 'A' Circuit High
Read more: https://www.autocodes.com/p0406_mercury.html