Confused about P0136 code

[Zero0575]

So, I know P0136 is a bank 1, sensor 2 code, no confusion there. What I’m confused about is that I can drive my runner every day locally, including short stints on the highway for several months/indefinitely without ever tripping the code, but if I go on an extended highway trip, say an hour or so, it will throw the trifecta of dash lights (CEL, VSC/TRAC)! I have no problem clearing everything, which I do when it happens, but it does get old, and obviously I’d like to correct it so it doesn’t happen at all. I’m running Thorley shorty headers, cats, and have spacers on the sensors already. Is it likely that the sensor itself is bad? Why does it ONLY trip in that one circumstance?

Question, do you have a scan tool? If so, you can monitor the voltage of your bank 1 sensor 2 vs your bank 2 sensor 2. I've learned alot about O2 sensors in the past 2 weeks while troubleshooting my issue (which is the same as yours, just on the other side of the exhaust)...

The voltage of the downstream O2 sensors should stay between ~0.1 and 1. If it drops below a certain voltage (I believe it is .03) for a certain period of time, the check engine light is tripped for low voltage. The downstream O2 sensor gets its voltage based on the changes in exhaust flow. The spacers that we use to remove the CEL for the doug thorley headers removes the O2 sensor from most of the flow, and sometimes removes it from too much of the flow which causes the low voltage code you're seeing.

For me, the voltage was running too low on bank 2 (hovering between 0.03 and 0.04 at idle and cruising), so I was getting that code.

The reason it is probably not happening when you're running around town is because you are stopping and going, so your exhaust flow is changing and the voltage is fluctuating beyond its lowest point often. When doing long highway drives, the voltage will remain at it's lowest, which in my case was too low. My fix ended up being removing the spacer just on the side that was throwing the code. Now the voltage, at idle and cruising speeds, sits right at 0.1 where it should be. Sorry for all of the posts on this thread, this has been quite a learning experience to get rid of one small code!

If you have a scan tool, I would recommend measuring those values of Bank 1 sensor 2 and bank 2 sensor 2. If you don't have a scan tool, get one off amazon for less than $20. Hope this helps!

 

[Tanviaggrwl]

Have you tried cleaning your MAF sensor? Sounds weird, but I recently got P0157 which is bank 2 sensor 2, and wouldn't throw that code til I got to highway speeds. I drove the dustiest (spelling?) trail of my life in CO recently auto clicker so I did some guesswork and cleaned my MAF sensor, no more codes.

For what it's worth I I have a similar setup to you, doug thorley shorties with spacers.

P0136 is a common OBDII code that occurs in the Toyota Camry. It is typically caused when the O2 Sensor voltage is not within normal operating range.

the only symptom of P0136 is going to be the service engine soon light. In some cases, there can be other symptoms as well. These symptoms include:
Rough running engine
Smelly exhaust
Service light on
Poor MPG
Most of the time, it’s not a breakdown risk. But, like anything that causes the service engine soon light to come on it is a good idea to have it fixed as soon as possible. Driving your vehicle for really long periods of time with P0136 can potentially lead to engine, catalytic converter damage.

The oxygen sensor itself is one of the most likely reasons that P0136 is triggering your service engine soon light. Although it is a temptation to replace it right away, it wouldn’t hurt to check out the wiring harness around it beforehand. See directly below.

It is possible to diagnose the P0136 with a multimeter. If you use the multimeter, you’ll know whether or not the voltage coming to and from the oxygen sensor is within spec, this can help you determine if it’s your Camry’s O2 sensor, or wiring harness that’s the issue.

If you don’t have access to a multimeter, it certainly wouldn’t hurt to check the wiring to between the fuse box and the Oxygen sensor first. If it ends up being a wiring issue, it’ll save you money over buying an unnecessary O2 sensor.

You can also use a voltage test light to determine whether or not the oxygen sensor is getting any voltage at all (they’re about $5 at Walmart). If it’s not getting any voltage, attach the test light to the harness plug and shake the wiring a little bit. If the light comes on, even for a second, you know that you have a short circuit causing the P0136 trouble code.

 

[Terminator03]

P0136 is a common OBDII code that occurs in the Toyota Camry. It is typically caused when the O2 Sensor voltage is not within normal operating range.

the only symptom of P0136 is going to be the service engine soon light. In some cases, there can be other symptoms as well. These symptoms include:
Rough running engine
Smelly exhaust
Service light on
Poor MPG
Most of the time, it’s not a breakdown risk. But, like anything that causes the service engine soon light to come on it is a good idea to have it fixed as soon as possible. Driving your vehicle for really long periods of time with P0136 can potentially lead to engine, catalytic converter damage.

The oxygen sensor itself is one of the most likely reasons that P0136 is triggering your service engine soon light. Although it is a temptation to replace it right away, it wouldn’t hurt to check out the wiring harness around it beforehand. See directly below.

It is possible to diagnose the P0136 with a multimeter. If you use the multimeter, you’ll know whether or not the voltage coming to and from the oxygen sensor is within spec, this can help you determine if it’s your Camry’s O2 sensor, or wiring harness that’s the issue.

If you don’t have access to a multimeter, it certainly wouldn’t hurt to check the wiring to between the fuse box and the Oxygen sensor first. If it ends up being a wiring issue, it’ll save you money over buying an unnecessary O2 sensor.

You can also use a voltage test light to determine whether or not the oxygen sensor is getting any voltage at all (they’re about $5 at Walmart). If it’s not getting any voltage, attach the test light to the harness plug and shake the wiring a little bit. If the light comes on, even for a second, you know that you have a short circuit causing the P0136 trouble code.

Yeah, I know the plug connector *may* be part of my issue because it looks kind of melted, and I couldn’t get it apart last time I messed with the sensor, and rather than risk breaking it, I carefully unscrewed it while connected.. When I reinstalled it, I carefully pretwisted the wires first so once tighter,the wires wouldn’t be twisted, if that makes sense. I wonder if I should just get a universal style sensor, and get rid of the connector altogether? Not sure if they sell replacement connectors, but obviously I’d prefer replacing the plug for future service ease, vs. just splicing it directly.

 

[Terminator03]

Yes, I actually do have a handheld scan tool, which I use to read and clear codes, and also have a dongle type and software for my iPhone which can read all of he sensor voltages, but haven’t tried it on the 4Runner yet, but what you mention here makes me want to try it, thanks.