2003 Lincoln Navigator back up sensor immediately and continuously beeps when vehicle is placed in reverse, even when there is nothing anywhere near the vehicle as it is backing up. Had Ford/Lincoln service department look at and they stated that the module is no longer working properly and would cost approximately $1,000 to fix. We asked if we could just have the sensor disabled. $1,000 seems like a large sum of money for something that is really not needed, as we seem to back up our other vehichles just fine without this sensor assistance. We were told if they would just disable the sensor that it would cause the check engine light to come on and stay on. Does anyone know if disableing the sensors really does produce a check engine light or are they just trying to get us to spend $1,000. Thanks for any assistance on this issue.

google 2003 Lincoln navigator manual
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https://www.lincoln.com/support/vehicle/Navigator/2003/owner-manuals/

Did you try looking at you tube videos they may have a video. Some are better then others. Depends which engine you may have also. Seen a video on the 2001 it's on the left side of the engine near the exhaust. You may also have yours there. If you have the new one you can follow the few wires and match the new switch with the old one to make sure they are the same before removing it

Lincoln Navigator 2003 2006 WorkSHOP Service repair manual Download

get your car fix right now

Check it for codes

You most likely have a couple bad COP Ignition Coils,
possibly a bad EGR Valve or TPS Sensor

All those are common ford & lincoln items

Change the oxygen sensors just before the exhaust converters
if you have 100,000 miles on it

Replace the Gas & Air Filter & clean MAF Sensor with CRC MAF
Cleaner

Install New Spark Plugs

All I suggested should have beeb done when you got it

All your vehicles as well---It is called Preventative Maintenance

Try this from my previous post....

Have a similar problem... My 2003 Lincoln Navigator was manufactured May 22, 2003 so it's the late model that came with the Intec 5.4 Liter DOHC V-8 (not the Triton engine).

I replaced the two front ride height sensors (one for each air strut) and replaced the one rear ride height sensor that controls the ride height for BOTH rear air struts. (Yours may have one ride height sensor for each of the rear air struts.) That solved the problem for a few months during the warm months, until the weather started cooling off. Then back to the same issue.

The front passenger air strut started releasing air from the solenoid (air block) making a "hissing sound." Replaced BOTH front air strut solenoids (connected at the top of each air strut). That also resolved the problem for a few days. After going all around the world, I discovered it's the Air Ride Control Module (ASM) that was the problem all along.

Sounds like it might have a bad height sensor.

If its automatic, you need a new transmission. Manual transmission, keep trying to switch gears and maybe it will slip into reverse. Or you could do what I do, don't pull into anywhere unless it's a slight hill that you can coast in Neutral backwards or have someone push you in Neutral.

This is a very common problem and depending on the code, its very likely a radar sensor. It is located in the bumper cover.

Check for Vacuum leaks near the intake manifold.

The navi has leveling sensors on both axles that are switches and are adjustable. Most likely these are out of calibration. DO NOT attempt to move or adjust these with the vehicle on jack stands. Vehicle could shift and fall resulting in serious injury.