Why on a 1990 town car the distance to empty will sometime read CO digital dash what does this mean?

On a 1990 Lincoln Town Car with a digital dash, "CO" in the place of the distance-to-empty reading likely means there's a problem with the fuel level sensor or its associated circuitry. The system can't accurately determine how much fuel is in the tank, so it displays a code instead of a distance. "CO" might be short for "Code" or a similar internal error message.

Here's why it might happen:

* Faulty Fuel Level Sender: This sensor in the gas tank measures the fuel level and sends that information to the instrument cluster. A malfunctioning sensor is the most common cause.

* Wiring Issues: Damaged or corroded wiring between the fuel level sender and the instrument cluster can disrupt the signal.

* Instrument Cluster Malfunction: The instrument cluster itself might have an internal fault preventing it from correctly interpreting the signal from the fuel level sensor. This is less likely than a sensor problem.

* Low Fuel: While less likely to show "CO" it's possible that very low fuel could cause a reading error.

What to do:

1. Check your fuel level visually: See if your gas gauge needle is erratic or pegged at empty. This will help narrow down if it's a sensor/wiring issue or an instrument panel problem.

2. Have a mechanic diagnose the issue: A mechanic can test the fuel level sender, wiring, and instrument cluster to pinpoint the exact problem and recommend the necessary repairs. This is the most reliable way to fix the problem. They might use a diagnostic scanner to read any error codes stored in the car's computer.

Don't rely on the distance-to-empty reading until the problem is fixed, as it's unreliable and could lead to running out of gas.