yota4life6

95 3.0 auto 4runner w/ 235k miles

One of the techs at the company I work for has a engine code scanner, so we hooked it up... I didnt have a CEL on but I had a hunch that codes were stored... The idle and performance is horrible and I just failed emissions yesterday.. IT SHOWED code #21 and 27#, which seem to be 02 sensor, "circuits", or heaters"..

Just as I am about to run out and get the 2 02 sensors to replace them, I wanted to check and try and get an explination on the "heater", "circuit", etc... Is this technical talk for "REPLACE YOUR 02 SENSOR(s)"??

Do i replace both 02 sensors and be done with it?

Please help asap, tags are expired and need to pass emissions..

thank you

TNRabbit

Replace both; check this site: http://www.sparkplugs.com

They have great prices on real Denso & NGK O2 sensors. Don't get crappy ones.

chevtruknut

You can test the voltage at the O2 Sensors if able, that would verify if bad or not. The "heater" they are talking about is the heater on the O2 sensor (It allows the sensor to warm up faster, getting your vehicle out of open loop quicker, think of it as modern day fast choke system. Please feel free to contact me if any more problems. Brad P.S. I agree with TNRabbit, don't buy the cheapest ones, you are throwing money away. a LITTLE more cost will get you a LOT more quality and life.

abecedarian

since you're getting codes for both O2 sensors' heater circuits, check you wiring...

chevtruknut

I agree with abecedarian. I always suggest that people do the codes twice (have found many were quirks) and always check the wiring, sorry for the incomplete advice. Good job. Brad