Repair Info - Emissions Repair Explained
Engine Exchanges
The specific regulations [external link] that apply to engine exchanges are complex because of the fact that it is not only the engine but also the engine’s emission control systems that affect emissions. However, the principle is this: you cannot make any change that would degrade the vehicle in terms of emissions performance. Vehicles are expected to remain in compliance with the emissions standards in effect for the model year of the chassis.
For example, you cannot take a 1994 vehicle and install an engine package that was built to comply with 1986 emissions standards. Also, you cannot take a 1994 passenger car and install an engine package from a 1994 light-duty truck. In either case, the emissions performance would be significantly degraded so it is not permissible.
You can exchange an engine package with one from the same model year or a later model year as long as it is from the same class of vehicle (eg. passenger car). In that case, the emissions performance will be comparable or perhaps even better than original.
The table below provides a quick reference of engine exchanges to help you determine if a replacement engine is legal or not. Engine calibration refers to the combination of engine and its complete emission control system. When this definition is applied to older vehicles with no on-board computer, the engine calibration includes all emission control devices. When applied to late-model vehicles with on-board computers, the engine calibration includes all emission control devices, the computer, all input devices, all output devices, and all associated wiring.
| Original Engine Calibration | Replacement Engine Calibration | Acceptable? |
|---|---|---|
|
* The replacement calibration must be of the same model year or newer. |
||
| Passenger Car | Passenger Car | Yes * |
| Passenger Car | Light-Duty Truck | No |
| Passenger Car | Heavy-Duty Truck | No |
| Light-Duty Truck | Passenger Car | Yes * |
| Light-Duty Truck | Light-Duty Truck | Yes * |
| Light-Duty Truck | Heavy-Duty Truck | No |
| Heavy-Duty Truck | Passenger Car | Yes * |
| Heavy-Duty Truck | Light-Duty Truck | Yes * |
| Heavy-Duty Truck | Heavy-Duty Truck | Yes * |
