Auto Electronics: Check Engine Light, oxygen sensor, dirt roads

Question
Can mud on the underside of your car cause the check engine light to come on? I recently had my car repaired, and the light went off. Then it came back on, with no problems to the car. Yesterday I rinsed the underside real good, got lots of mud off. Today, the light is off. I ride dirt roads a lot, so I thought this might be the culprit. What do you think?

Answer
Sheene, I have learned over time, that anything is possible in this business. If the mud were to get into an oxygen sensor electrical connector or for that matter any other connector, it could disrupt the signals sent to and from the engine control module. It's even possible that if mud were to cake on the catalytic converter, it might cause it to overheat. The check engine light is controlled by the engine control module, based on monitoring tests the module runs constantly. If and when it detects a problem that could cause excessive emissions, a code will be stored and the light will come on. If the light comes back on to stay, have it looked at by a reputable shop. Hope this helps you. Don.