Okay so about two weeks ago my engine light came on. P0131. Bank 1 sensor 1 O2 sensor, low voltage. So I replaced the sensor. Today, codes P0131 and P0151 (both upstream O2 sensors low voltage), were thrown when my engine light came back on. What could be causing this? Car seems to be running fine. Someone told me it could be a dirty Mass Air Flow sensor, which could be throwing off the readings of the upstream O2 sensors? That's odd that they both went off at the same time, especially after I just replaced the one. Another thing I've heard is a vacuum leak.

Not sure if this matters, but the engine light came on under the exact same conditions both times. After about an hour of spirited driving with fairly regular wide open throttle pulls.


What do you guys think?

 

Maybe leaky injectors?

 

Any way I'd be able to check for a leaky injector without a scan tool?

 

Don't know.