Main IndexAuto Repair Home Search Posts SEARCH
Who's Online WHO'S
Log in LOG

Search Auto Parts

Is this a bad o2 sensor (voltage reading)

  Email This Post

New User

Sep 2, 2020, 5:10 PM

Post #1 of 2 (172 views)
Is this a bad o2 sensor (voltage reading) Sign In

I was getting a fault code on my 2007 toyota yaris P0171, car bogs down runs rough and run rich. i we cleaned the map sensor still getting the code voltage reading on the 4 wires are .9v on 3 wires and 1.7v on the other wire, is the sensor faulty, any help would be much apprecited

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 2, 2020, 5:39 PM

Post #2 of 2 (168 views)
Re: Is this a bad o2 sensor (voltage reading) Sign In

I deleted your duplicate post. It's not necessary.

The code is indicating a lean condition,not a rich one. You don't understand how an 0/2 sensor works. There is only one sensor wire and it constantly fluctuates. Two of the wires are for the sensor heater. One of those is a ground and the other should have 12 volts with the key on and unplugged.

The way you test a sensor is by reading the data on a scan tool and artificially enriching the engine to see if the sensor responds.

There is no reason currently to blame the sensor. What you need to look for is the cause of the lean condition. Vacuum leaks are the most common causes.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

  Email This Post

Feed Button

Search for (options) Privacy Sitemap