This is typically an electrical wiring connection issue, either at the engine controller or at the sensors being monitored by the manufacturer.
It can occur if:
The wrong EGR sensor is installed on the vehicle. Verify with the manufacturer for the latest.
A bad ignition module is present.
Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
The cost to diagnose the U1009 Mercury code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.
When the PCM is unable to communicate with any other controller on the bus network at any time while the ignition switch is in the “Run” position.
This is a manufacturer-specific fault code and can be used for several different faults, depending upon what the manufacturer wants to use it for. The Powertrain Control Module (PCM) communicates over the Serial Communication Protocol (SCP) bus network or J1850 bus. This is a medium-speed bus communication system and is fault-tolerant, which means any type of intermittent/loose connection at these controllers will cause this code to set in memory, but will still operate, provided a data path is available. When the PCM is unable to communicate with any other controller at any time while the ignition switch is turned on, code U1009 will set. This is the typical reason for this code to set.
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