Air mass sensor and oxygen sensor

ATTILAKILLA1

MEMBER
MAZDA 626

I just recently bought a 99 mazda 626, I had it taken to autozone for a diagnostic test. I was told that I had codes reading a failed Air mass sensor and both of my oxygen sensor were blow. The car has 160,000 miles on it and it an automatic tranmission. I know that both of these item need changing around 100,000 miles. My problem is that I can't find the air mass sensor and the oxygen sensor. Can you please help me out. I was planning to replace this stuff on my own. Just show me in the right direction.

1 Reply

FAIRRACING31

MECHANIC
150 POSTS

The Mass Airflow (MAF) sensor is located in the air intake duct. That is the part that goes from your airfilter box, to you throttle body. The sensor uses a hot wire sending element or potentiometer, depending on model, to measure the amount of air entering the intake system. It sends this info to the PCM as a voltage signal, which in turn, calculates the required fuel injector pulse width.
The Oxygen sensor (O2S), the primary O2 is located in the exhaust manifold or pipe before the catalytic converter. The secondary O2 is located in the exhaust pipe after the catalytic converter, follow the harness to locate the connector. The O2 moniters the oxygen content of the exhaust gas stream. The oxygen content in the exhaust reacts with the O2 sensor to produce a voltage output which varies from 0.1-volt (lean) to 0.9-volt (Rich). The PCM constantly moniters this variable voltage output to determine the ratio of oxygen to fuel mixture. Which is also controlled by the injector pulse.