Christian8

Ok guys, i got a serious problem.
I went to go get my inspection today and it didnt pass. My check engine light apparently got activated when they moved my RX into the garage for the test. I went to Autozone and they told me that it was OBDII (ALPHA) P Code P1153. (bank 2 fuel control shifted lean). When i asked about the code, they had no clue as to what might cause this. I'm a little skeptical about this code because when i began to search it online, it appeared as a Ford code. Should i trust this? Has anyone ever seen this code before? Thanks for the help.

C. Morales

Lexmex

You're right, does not even exist in the manual.

Closest one is a P1155 which is an A/F sensor Heater Circuit Malfunction, Bank 2 Sensor 1. This is the front A/F sensor in the photo below on the manifold just in front of the engine block.

Now, did anyone try to reset the light as in turning it off, or is still lit?

Christian8

It goes on and off , so what i did was i took the negative off the batt. and then drove it 100miles so that the computer would register information, but apparently the light came back on. As of this moment, it's still on.

Lexmex

The most realistic thing that will keep the light on is the sensor itself, which may require replacement. However, if there is crack on the manifold in the area near the sensor, that may also cause an error, as the sensor measures certain ranges and issues. I would try reseting it one more time and also pull out the EFI fuse for a second (as we have mentioed before) along with both the positive and negative battery cable and then see what happens after a day. You may be able to sneak it in for inspection without the light going off.

Christian8

Thanks for the help. Much appreciated. I'll let you know what happens afterwards.

Tammy

P1153 A/F Sensor Circuit Response (Bank 2 Sensor 1) (Toyota)

You might try to unplug and replug the wire to sensor 2 (closest to the radiator).

Additionally, inspect the sensor wiring for any burning or damage.

As previously referred, the down pipe of the exhaust header for the forward #2 cylinder bank, is prone to crack at the point where the pipe takes an accordion shape as it is formed toward the rear of the vehicle.

The 2000+ pipe design uses a steel mesh design as a replacement.

Lexmex

Now, I did have a very minor crack (I will take a photo later of our weld) shown here, though it was just a tiny hole.

Lexmex

What Tammy is referring to is something I could not get fixed down here except by the power of a welding torch.

Lexmex

Of course cracks and holes are prone to happen. This was something we took care of last week before I did those midpipe mods on Saturday.

The other place where the exhaust can leak, even on a perfectly stock system is at the meeting of two joints.

Christian8

I believe that my problem is what Lexmex mentioned. I might have a crack in the header by the sensor. For a while, ive had this weird sound come out of my exhaust, like if the unit was torn or something. You guys think the sound im talking about could result from a crack in the header? BTW, my check engine light came back on today after 44 miles of disconnecting the neg. What would you guys suggest?

Lexmex

Last thing we would want you to have to do is shell out $$$ for the A/F sensor (shown for the location below).

Now, I rarely get CELs and usually they are related to how much air I am throwing in, not exhaust.

My uncle, Hangar1 and I noticed this area now welded was belching a little exhaust on a tiny hole on the crack (no CELs from this) and also at that accordion joint we welded earlier, but very difficult to hear it. You need to put your hand a little distance away from the pipe and then you could feel it.

Yet, the sensor may have indeed gone kaput and need replacing.

There is another way, and you may not need to go to Lexus. Some more advanced OBDII scanners (that good independents should have) can read the readings coming from both of these A/F sensors to see exactly what is going on and determine if indeed you have a rotten sensor.

Christian8

ok, so i went back to autozone b4 going to toyota and the code that i got today was a P0171 which is too lean for bank 1. My previous problem was bank 2. Both places are saying that it would be best for an injector flush. Funny thing though was that right after leaving from toyota, my cel got deactivated. First thing imma do 2morrow is go to that inspection and get it b4 the light comes back on.
I really havent had the time to REALLY check the pipes, but there is a crack(?) by the bolt (under the sensor in the last pic Lexmex posted). Like i said, i havent had the time to check, but would that "crack" affect anything?

Lexmex

Ah, the infamous P0171 error. That is an RX300 favorite and my personal favorite (for me it means I am shoving too much air in for the amount of gas, an achievement I love being at this altitude).

Yes, that error can deactivate itself. I watched it do this a few years ago on a trip up to Texas right about San Luis Potosi just after leaving a gas station. Often times for most it is just loose gas cap, the A/F sensor detects a minute variation (as must have happened in your case), MAF sensor dirty, IACV dirty or that the A/F sensor itself (shown below in the Bank 1 location) is acting funny. In the last case, one can check with more advanced OBDII scanners what readings it is getting.

The crack, only if big enough, can throw a light. In my case, nothing, but after welding it, torque went up (along with that other area that we welded).

Now, with inspection, even with the light off, the computer often stores the old code, you can eliminate this without messing around with the readiness cycles (something they check on OBDII inspections) by just having Autozone scan and then delete the old code. I know that some states allow one stored code even if the light is not on, but not sure about your state.

justfixit

P1153 / Bank #2 Air fuel ratio sensor slow response. Sensor needs replacing.
P0171 / System lean Malfunction. Dirty or defective Mass air flow sensor
Clean MAF sensor hot wire.

Christian8

Ok guys,
lol, the cel remained off today so i decided to try the inspection again, and it passed. lol. Does colder air have any effect with anything? The outside temp has gone from high 80s-low 90s down to low 50s. (Farenheit). I'm getting an injector flush on monday so hopefully that will help.