O2 sensor [emissions test]

My 2009 Tacoma is due for it's annual state inspection (TX) and when I took it in last Friday they were unable to PASS it because the O2 sensor being in 'Not Ready' status.

Was told I should just drive it and run it through a drive cycle. Miles and days later the O2 sensor is still not showing 'Ready'.

I disconnected the battery a few months back to clean the terminals but that was at least 3000 miles ago. Wouldn't the sensor have reset to 'Ready' by now?

Any advice? Thanks.

 

Question #1- do you have a code reader that can check for a pending code? One of the only things I can think of is that there's a pending code, perhaps one that requires a few consecutive failures, and your parameters are right on the edge of passing or failing, so it's not tripping the CEL because once out of however many drive cycles it's seeing it pass. Don't think it's likely, but I don't think any of the other possibilities I'm thinking are, either...

2. Do you have a freakishly short commute and never drive more than a few miles at a time? The readiness tests have various parameters that have to be met for all sorts of things- run time, starting coolant temp, reaching a certain coolant temp, max RPMs, and so on. I wouldn't think this would be the culprit, it's usually evap tests that have really weird requirements, but I'm not that familiar with this truck... mine has been trouble-free so far.

3. You don't have a dead-ass battery that has to be jumped often, right? Killing the battery (below 9V or so) will reset the memory just as well as disconnecting a cable. I'd imagine you'd know (and mention it) if so, but stranger things have happened...

 

OP what engine do you have? You may have up to 4 oxygen sensors you are dealing with. Do you know the code or which 02 sensor is giving the fit?

 

02 codes like the P0420 or P0430 for example, when they fail initially will set a "Pending" DTC. After 2 or more fails, then it'll illuminate your CEL. The frustrating bit about them is that they cant be cleared using an OBDII reader like most DTCs. If my memory serves me correctly, in order to clear that "pending" DTC, you'll have to start your vehicle and let it idle for about 30 seconds, then drive for about 10 to 15 minutes reaching speeds at a minimum of 35 MPH/3000RPM then stop and idle for another 30 seconds before shutting off. Repeat this a minimum of 2 times, possibly 3, I cant remember exactly and the "Pending" DTC will clear itself. Pulling the battery wont clear the code. Trust me, I'm in the same boat. I pulled my Cats and I'm currently running a URD Rear 02 Sim thats been installed for at least 8 years now. I'm sure thats my problem since I'm getting continuous P0420 codes with P0430 inttermittent. My guess is that where I have the module stored is exposed to corrosion so I need to check the electrical inside it but thats for a later date.

Bottom line, check your OBDII and find out what sensor is giving you issues. Replace it, do what I said above to clear the code and you should be golden. O2 Sensors are kinda pricey but you gotta pay to play.

-J

 

I'm having the same issues with my truck. The p0430 showed up when I hooked up the code reader, but now the CEL is not on anymore... and I didn't reset the codes...
Also I have no idea which O2 sensor needs to be replaced...
I just bought a 2nd gen

 

The p0430 typically means that you have a catalytic that is no longer within the efficiency threshold. This code is most common when cats are going bad, or ppl run long tube headers without cats.

What year is your 2nd gen? If you have an 05-13 you can get some URD o2 simulators to get rid of the CEL. The alternative would he to replace your stock manifolds since you're in California and need to pass smog.

A cheaper troubleshooting alternative to the ones mentioned above would be to buy some o2 sensor anti foulers and see if that fixes your issue. They can be had for under 20 bucks and they basically move the o2 sensor a little further back and out of the exhaust stream. This is a good way to isolate the problem and figure out whether the cat is bad, or if the o2 sensor needs to be replaced. How many miles are on the truck?

Edit: the urd sims dont work as well on the 14-15 yr models. If you have a 14-15 HP tuners can disable the code

You shouldnt have any drivability issues with this code - is that correct?

 

I've heard that using tuners to disable the code will just prevent the CEL from illuminating. If you were to hook up a reader it would still display the code as either a full blown CEL or as Pending. I might be wrong on that though.

-J

 

Im not sure on this either. I deleted my secondary air injection system with hptuners and i have an ultragauge plugged in everyday and it never throws any codes. Im not sure if its any different with o2 sensors and other things though.

 

I have one of those Bosch bluetooth OBDII readers constantly plugged in too. Have you ever hooked up a different OBDII reader and checked to see if you have any codes? Im just curious.

-J

 

No sir, never have tested it with another obdii reader.. i think i remember reading in the hp thread that what you mentioned about the code still showing up but just not illuminating the CEL only happens if its throwing the code and you havent cleared it before you disable the code with HP. So in other words, the computer has stored the code and still shows it when a reader is plugged in but its just no longer causing the light to pop. I think if you clear the codes, then disable them with hp that it should put you in the clear. That has been my experience with it at least

 

Mine is a 2005. I just went ahead and replaced the O2 sensor that I thought might be going bad. I will have to check out the anti foulers that you are talking about. That sounds like a good plan to me. If I put the anti fouler in instead of replacing the O2 sensor, would that essentially tell me that it was the sensor as long as the CEL doesn't come back on?

 

I think if the anti fouler fixed it, it would indicate that the cat is bad

Heres a thread with some info

https://www.tacomaworld.com/threads/another-p0430-bank-2-05-tacoma.157627/