Jim Grant's Tech Tips
98 Mazda Protégé, Engine Bath
Q: I pressure washed the engine on my ’98 Mazda Protégé with a 1.5 liter engine. The Check Engine light came on. I disconnected the battery and the codes were gone but the next day the check engine light is on again. Any idea what could be wrong?
Pressure washing and/or degreasing an engine can cause a pile of trouble on a computerized vehicle. Many of the computer sensors on today’s engines do not use electricity like a light bulb or electric motor. The sensors just change a voltage signal/value that is read by the computer. A pressure washer can force water and cleaning solution past the weather seals on the sensor connectors. Because water, and whatever cleaning solution, is a conductor of electricity it can affect and alter the voltage signals seen by the computer from the sensors. The computer may guide you in locating which sensors or sensor connector you flooded. If you’re lucky, it’s just a matter of cleaning and drying the affected sensors or their connectors. If you’re unlucky, you’ll be replacing some parts