BWD - Motorist FAQ

Frequently Asked Questions

The ‘Check Engine’ light comes on and stays on while my vehicle is running. What does that mean? Do I need a ‘tune-up?’ Is my ignition, fuel injection or emission control system malfunctioning?

Servicing the engine management systems on today's computer-controlled vehicles is more than just a tune-up performed at regular intervals. That's why the ‘Check Engine’ light alerts you when there is a problem in your vehicle. When it lights, it means that your vehicle's on-board computer (known as the Electronic Control Module or ECM) has detected a problem in one of the many systems it monitors and controls. The problem may be minor, but it could be serious.

What if the ‘Check Engine’ light comes on but my car is still running okay?

Not every problem with your vehicle results in noticeably poor vehicle operation. When the ‘Check Engine’ light comes on, it means that some system in your vehicle, perhaps ignition, fuel

injection or emission control, is not operating at peak performance…even if your vehicle appears to you to be running normally.
• Hard starting, rough running or stalling may occur, but not always.
• The ‘Check Engine’ light also alerts you to problems like poor gas mileage, reduced performance or increased vehicle emissions.
• Some problems evolve so slowly that you get used to them, and they seem “normal”. That’s why regular tune-ups and visiting your trusted service technician at the first sign of trouble is your best defense against costly problems in the future.

What does the on-board computer do?

It processes information it receives from the many sensors that monitor the systems operating on your vehicle. Here is a short list of just some of the sensors that you might find on your vehicle. These sensors provide information to your vehicle's on-board computer about how the fuel delivery, spark timing, emission controls and other systems perform.

• ABS Sensor
• Accelerator Pedal Sensor
• Ambient (Outside) Air Temperature Sensor
• Barometric Pressure Sensor
• Coolant Temperature Sensor
• Camshaft Sensor
• Crankshaft Position Sensor
• EGR Valve Position Sensor
• Knock (Detonation) Sensor
• Manifold Absolute Pressure Sensor
• Mass Air Flow Sensor
• Oil Level Sensor
• Oxygen Sensor
• Throttle Position Sensor
• TPMS Sensor
• Transmission Speed Sensor
• Vehicle Speed Sensor