Suspension problem
2003 Lincoln Navigator V8 Four Wheel Drive Automatic 64,433 miles
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Hello,

I have a 2003 Lincoln Navigator and It has the "Check Suspension light on the dash. I took it to the mechanic and he put it on the module and error code "C1991" came up and it said: "Module Calibration Failed." The mechanic replaced the height sensor and the solenoid was also replaced. The "Check Suspension" still remains on the dash.

What is this code and how can this problem be fixed?

My suspension seems to be working because my SUV raises and lowers itself whenever it needs to. The compressor is working.

Thanks in advance