Mass Air Flow (MAF) Sensor Voltage?

[biggles99]

Hello,

I have a check engine light (CEL) code P0171 on my 2000 Corolla, which indicates that the fuel injection system is too lean.

Everything that I have read so far indicates that the MAF sensor is the place to look first. I am following what it says to check as far as the Haynes Toyota book talks about.

When I am checking the voltage as the car runs, I am able to get it to read 2 volts when the car is idling and 2.5 volts when you press the gas down a decent amount.

What I don't now is, is that enough of a change to tell if it is working correctly? I don't know what it should be exactly either idling or at certain RPMs.

Either way, maybe I should just change the MAF sensor anyway, considering what other people have wrote

Thanks,

Tim

[tech8]

Usually it is just dirty, and you can just clean the Mass Air Flow sensor, and it usually fixes the problem.

You can get some electrical cleaner spray or even use brake cleaner.

I use CRC QD (Quick Drying) Electrical Cleaner (about $4 at Kragens).

CRC also sells a Mass Air Flow sensor spray cleaner (but to me, it's the same ingredients as their CRC QD Electrical Cleaner spray), also about $4.

Removing the Mass Air Flow sensor is usually just unplugging the wire connector, and then removing the 2 philips head screws. Pull it out and spray the fine thermistor wires inside the unit, and around the other areas of the unit. (The wires are delicate.) Let it dry completely, and then reinstall. Reset the Check Engine light before or after you clean the MAF sensor.

A new MAF sensor is around $150. So, I feel better to just try cleaning it first for a few bucks.