Skip the auto shop - Our mechanics make house calls

Q: What value should the MAF signal be at idle?

asked by on

I'm testing the mass air flow sensor, what is the known good spec for the signal to the ECU at idle?

My car has 212000 miles.
My car has an automatic transmission.

Here is a breakdown of the wiring color codes, and the associated voltages on each, for engine running and ignition on. The signal from the mass airflow sensor should steadily sweep from 1.9 to 5 volts as you press and release the gas pedal.

TERMINAL

B/Y (Power supply) G/O (Burn-off) G/B (Air flow mass) G/Y (Ground) B/O (Ground)

IGNITION ON

B/Y - Approx. 12V G/O - 0V G/B - 1.0 - 2.0V G/Y - Approx. 0V B/O - Approx. 0V

ENGINE RUNNING

B/Y - Approx. 12V G/O - 0V G/B - 1.9 - 5.0V G/Y - Approx. 0V B/O - Approx. 0V

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Truck will start but dies 2 seconds later

Hi there. You are on the right track. This sounds like a fuel pump problem. Though there are other things that can cause this, the series of events that you mentioned are the most likely causes. I would test the...

Q: Will the bolt pattern match up with a '98 Mazda B3000 motor to my '88 transmission 1988 Mazda B3000

Hello - unless your '88 has the M5OD-R1 5-speed transmission, I don't believe this swap will work. There were simply too many engine changes over the 10 years, and the M5OD transmission is one of the few common elements. You...

Q: Audi A4 '08 is jerking and check engine light flashes upon acceleration, any idea what could be happening?

This may be related to a faulty throttle position sensor or potentially a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.