What does water intrusion cause in relation to MAF signal voltage?

Water intrusion affects the Mass Air Flow (MAF) sensor's ability to accurately measure the airflow entering the engine. When water contaminates the MAF sensor, it can create a false indication of the airflow, leading to an improper air-fuel mixture. Typically, this results in a rich condition.

In a rich condition, there is too much fuel in relation to the air being supplied to the engine. The MAF sensor, thinking there is less airflow because of the interference caused by water, signals the engine control module (ECM) to deliver more fuel. This excess fuel can cause issues such as increased emissions, poor fuel economy, and potential engine performance problems.

While water intrusion may also contribute to a rough idle due to the imbalanced air-fuel mixture, primarily, the direct effect of water on the MAF signal voltage leads to the creation of a rich condition. Therefore, the best understanding of water intrusion's impact on the MAF signal relates to the rich condition caused by the erroneous readings from a compromised sensor.