O2 Bank 1 replaced

Had check engine lite activate. Got checked at Autozone was told I had code P0402. They have me a print out saying the O2 sensor Bank 1 need to be replaced. I replaced it. Do I need to clear the check engine lite some way to get it to turn off or could there be another problem?

 

If you unplug the battery for a few minutes it will clear the code. If it comes back after that then you have another problem. I think it should self clear after a few drive cycles or a certain amount of miles too, but I'm not sure how long

 

Excellent. I'll give that a try. Appreciate the advice.

 

I had the same situation with the code P0031 which translates to HO2S Heater Control Circuit, Low Bank 1 Sensor 1. After ordering a sensor from Toyota & installing it, I disconnected the battery for 5 minutes. That cleared the CEK warning light & it stayed off. Disconnecting the battery before changing the sensor & reconnecting it, would turn the CEL off, but it would come back on after a few minutes of operation. The electrical plug connection is a bear on a 2004 gearbox taco as it is on top of the transmission, bolted down. Good luck with your problem.

 

Well cleared the check engine light and all seemed good. After driving for couple of miles the light came back on. Guess I'm back to checking codes.

 

I'm sorry to hear, but your first mistake in my book is listening to Vato Zone,,, the code just points to the direction of the problem not the exact source. Plus, even it is the O2 sensor, I don't think the aftermarket one will work good enough to satisfy the computer, if it does, not for long. I would diagnose the issue, look at a flow chart in the FSM for the code, that'll help you out.

 

Hi - I'm Dave and live in Saugus, CA, driving a 2004 Tacoma extended cab 2-wd with 3.4L engine. Purchased this truck new in So. California, it now has 114,750 miles on the odometer.

Three weeks ago, the CEL threw a P-0031 code, indicating a bad up-stream A/F Sensor. The bad sensor Toyota p/n 89467-35060 was removed. The OEM replacement starts at $196 on Amazon, $280 at the dealer, but many vendors on Amazon, Ebay, auto parts stores and posts state that the Denso p/n 234-9001 is a valid replacement for the OEM Toyota part. NOT so.....

I purchased the Denso part and installed it. The truck CEL extinguished, but the engine surged and pulsated at all speeds. Not good. A replacement Denso unit was sent, installed, and with the same results. Not really driveable, but the CEL lite was OUT.

Last week I bit the bullet and ordered the OEM Toyota part number 89467-35060 for almost $200. In ten minutes it was installed and the truck runs like new.

Hope this helps someone in a similar predicament.

 

Welcome to TW.

I think you should show us that dragster.

 

Denso A/F sensor

$135 234-9001 Upstream Air Fuel Ratio Oxygen Sensor with 10.6” 4-Wire Harness, for Auto Trans Equipped Vehicles

234-9001 is for the regular, no CARB required Tacomas, and is routinely used as correct replacement sensor. The Cali CARB compliant Denso part number, I believe, is

$153 234-9002 Air Fuel Ratio Sensor

234-9002 or

$170 234-9003 Air Fuel Ratio Sensor

234-9003. Sorry you missed out on the money savings with this. It's definitely not easy to find this info.
But you are correct, 234-9001 is not a replacement for 89467-35060.

 

Thanks cruiserguy
I thot I had researched this, but what you say is exactly what my Toyota dealer friend surmised, and that is that California trucks are different. Would appreciate info as to which Denso part is the one to use in this case, either 234-9002 or 3....for the future and others here in California. Not only do we in California get to purchase the expensive sensor, we also pay a buck or more per gallon for gas and $100 more per year for registration! The plus in all this is a high-speed rail system that we desperately need!!

Hey T4RFTMFW
For info on my second dragster, take a peek at http://www.frontenginedragsters.org/photos3.htm and don't believe everything about the hacksaw! My article was edited by someone else. Sure was fun building and driving these beasts. Then I put twin turbos on the 327" in my Model A tudor, seen at
https://www.theturboforums.com/threads/1931-ford-tudor-327-sbc-twin-turbo.375157/ ....the fastest street car I ever owned or driven.

Have spent a lot of time trying to figure out how to put a turbo on my 2004 Tacoma 3.4L. Everything is easy from scratch to weld, mount, and the downpipe/exhaust is simple, but to retard the ignition when it goes into boost is not easy to do, controlling the fuel delivery is complicated, and it would never pass CA smog. I'm spoiled because of the Model A project shown in the above link.

 

@Bentrodder

 

Well lesson learned I think. Replaced the bank 1 sensor with a Denso. Was able to drive briefly and check engine lite came on. Had it checked again was told catalytic converter was bad. Had new on installed. Drove briefly and lite came back. Checked it again and said senator in bank 2 was bad. So replaced that sensor with a Denso. You guessed it check engine came back on after about 10 miles of driving. Not had it checked yet so not sure what might wrong but after the fact research makes me think the Denso sensor or sensors may have failed. Seems Densos are known for failure. If it is the sensors guess I'll go with OEM unless I find that something may have caused it to fail.

 

Denso makes the OEM sensor for Toyota.

So when the malfunction indicator lamp turns on, it never says something like 'sparkplug #3 is bad, replace it' or something like that. The ECM can't know a part is bad or good. It only monitors the values of that certain system through sensors. So for example, your MIL turns on and you get the code read, it will say a specific code and that specific code number is important. Let's say you get P0402, this means 'Exhaust Gas Recirculation Flow Excessive Flow Detected'. It doesn't mean the EGR valve is bad, per se, it specifically means the ECM, for some reason, got a value of EGR flow that was higher than it's programmed range. There can be many signals from many sensors that go into that decision to trigger the MIL.
I guess simply saying, if the MIL is triggered by a reading from a sensor, (02 sensor, temp sensor, etc) it doesn't necessarily mean that sensor is bad. It can be, but correlation doesn't always equal causation. Sorry for the novel.

 

Thanks cruiserguy for the explanation of how it works. I'm capable of doing the physical part of the repairs but not so much up on the theory behind. I'm going to get it checked again and see what comes up now. I'm hoping it comes up with a different code than before, I would rather spend the money to replace a different part than replace something already replaced once already.

 

Sounds like a solid plan, let us know what the code is when you find out

 

According to the Denso website:

$135 234-9001 Upstream Air Fuel Ratio Oxygen Sensor with 10.6” 4-Wire Harness, for Auto Trans Equipped Vehicles

234-9001 is for Automatic transmission

$170 234-9003 Air Fuel Ratio Sensor

234-9003 is for Manual transmission

Their site does not show

$153 234-9002 Air Fuel Ratio Sensor

234-9002 as a part available for my 2003 / Toyota / Tacoma / 3.4L, but if I search for that part number it comes up. It does not show details about the application.

 

Cool. So the

$153 234-9002 Air Fuel Ratio Sensor

234-9002 might be the sensor for Cali emissions spec tacos?

 

Not sure about that. It's looking more like the 234-9002 is for the 4-cylinders...

 

Well had codes reset after replacing both banks O2 and the catalytic converter. Light was off. Drove approx 5 miles and it came bac on. Had it scanned again and code says bank 1 O2 sensor circuit malfunction. Any suggestions as to what might case the O2 to malfunction?