O2 sensors

How many O2 sensors does a 2003 toyota tacoma have?

 

v6 or 4 banger?

 

3.4L V6

 

you have 2 02 sensors

 

1 upstream (before cat) and 1 downstream (after cat)?

 

yes that is correct

 

The upstream is referred to as an "Air fuel ratio sensor" and the downstream is an "oxygen sensor" but both are commonly referred as o2 sensors.

 

Had a P0031 code. HO2S Heater Control Circuit Low Bank 1 Sensor 1. Replaced the upstream sensor. Now get P2238 code. O2 sensor Positive Current Control Circuit Low Bank 1 Sensor 1. Any suggestions?

 

Did you get the correct sensor? As stated above the upstream (sensor 1) is an air/fuel ratio sensor and operates differently than a standard oxygen sensor.

 

I'll have to check on the sensor that I ordered and received. It was supposed to be the upstream sensor, which means it should have been the air/fuel ratio sensor.

 

Avoid ebay and Amazon sensors
Lots of counterfeits being marketed as Denso identical OEM replacements
https://densoautoparts.com/find-my-part.aspx

 

Possible wire harness damage or a corroded plug .

Knock off denso poor quality control in the plug pins not making contact

 

BTW Butt splicing sensor wires is not advised but sometimes previous owners did it.

 

I had a P0031 and replaced my upstream sensor with a rockauto denso.

I now have CEL P0136 ( heated oxygen sensor HO2S 2, bank 1- circuit malfunction). I am planning on replacing the second sensor as my next step.

The other variable I have is my exhaust is new from the first cat back because the old one was rusted to hell. Replaced with walker cats from Advanced auto and a MRBP exhaust.

 

Has anyone posted side-by-sides of Denso knock-offs from Amazon for reference?
I bought some a while ago before hearing people were having issues. Thinking about fitting em this week.

 

Interesting question. Or did you search threads by me.
Very few could tell the difference between an O2 and A/F sensor.
No one could identify counterfeits.
That's why I post this link
https://densoautoparts.com/find-my-part.aspx

Sppot the fake

https://www.tacomaworld.com/threads/spot-the-fake.632516/#post-21712014

 

I hadn't seen that thread thanks. I'll check mine tomorrow. I didn't buy via a 3rd party Amazon seller but straight from Amazon and my other Denso products through them have been good so far, minus my radiator that was messed up in shipping but that's another. We'll see. Such a bummer that it's an issue.

 

If the Amazon ad says OEM identical replacement I wouldn't be adverse to purchase. All DENSO Identical replacements will come with the good gasket. The fakes came with NO gasket. One fake a/f was an O2 with an a/f connector. A/f and O2 have different connectors. The fake #2 sensors lacked the rubber floorpan plug which comes on Real DENSO downstream O2s

 

Thanks for the info. It'll be interesting to see what happens.

 

Since Napa started selling Denso Sensors they are my Go to .

If I screw up or They do they Come pick it up next delivery.