2009 Chevrolet Impala Owner's Manual - Page 148

Speedometer and Odometer The speedometer shows the vehicle's speed in both miles per hour (mph) and kilometers per hour (km/h). The odometer shows how far the vehicle has been driven in either miles (used in the United States) or in kilometers (used in Canada). This vehicle has a tamper-resistant odometer. If the odometer displays ERROR, it probably has been tampered with and the numbers might not be accurate. If the vehicle needs a new odometer installed, it must be set to the mileage total of the old odometer. If that is not possible, then it will be set at zero and a label must be put on the driver's door to show the old mileage reading of the vehicle when the new odometer was installed. Tachometer The tachometer displays the engine speed in revolutions per minute (rpm). Notice: If the engine is operated with the tachometer in the shaded warning area, the vehicle could be damaged, and the damages would not be covered by the vehicle warranty. Do not operate the engine with the tachometer in the shaded warning area. 3-26