lexus300rb

On code reader P1130 comes up. A/F sensor B1S1. I take it B1S1 sensor is at the back of the engine near firewall. What Denso part # is it? I found Denso part 234-9009 and Denso 234-9007. Can you use the same 234-9009 for B1S1 and B2S1 sensors? Or lead me in the right direction.

bearbrew

The B1S1 and the B2S1 both use the Denso 234-9009 sensor. The most reasonable place to purchase has been through Amazon.com at about $115.00 each. Either purchase the Denso sensor or the original from Lexus which is the same as the Denso but at a much higher price.
The B1S1 is the sensor on the rear bank (below the firewall) and is a little harder to replace but with patience it is doable. The connector can be difficult to disconnect but not impossible.
Do a search for P1130 or B1S1 and you will find a DIY on replacing the sensor.

Bear

chenxingha

You may want to check for small exhaust leak before replacing the B1S1 A/F sensor. The likely place in the exhaust system is between the main (raer) catalystic converter and the front Y connecting pipe, where two bolts compressing two spings to hold the connections. Since it is a flex connection, the joint often moves and break the inner seal.

Use a telescope mirror and a flash light to check the all sides of the joint - you should be able to see the seal sitting in the joint seat all around. If the seal has certain section missing at the seat, then do a cold start test to see if there are water or white steam coming out of the joint. If repair is needed, the seal is less than $10 and with another $7 for the pair of bolts.

I had the P1130 code on one of the two 2000 RX300 AWD in the house a little while ago. I ordered the seal and bolts to fix the exhaust leak and the A/F sensor to replace B1S1. The seal and bolts came in first and fixed the leak. The "Check Engine" light has since stayed off, hence no P1130 code read, for three months now. I am still holding the Denso 234-9009 sensor replacement part ($97 free shipping from Amarzon) until the one on the vehicles go bad.

Just my two cents.

carguy07

How can a leak that far down stream from a sensor cause it to kick a code?

lexus300rb

Since my original post I have ordered a code (scanner) reader. In the mean time I'll check the gasket downstream from the sensor. It doesn't make sense though that the gasket downstream of the sensor to cause a P1130 code.

RichardT

I replaced my cabin filter yesterday and it kicked a P1130 error code. Is that possible? The filter however is a different shape (Bosch) than the original.

salimshah

If you mean cabin filter ... in the glove-box then, it should have no effect on CEL.

When you say different shape .. what exactly do you mean .. the filter must physically match to seal and separate the two sides.

Salim

chenxingha

An exhaust leak would affect the vacuum readings in the exhaust system.

Not long ago in Feb this year I fixed an exhaust leak between the y-pipe and main cat. converter (where the spring-bolt combination is used to connect the two pieces) and the check-engine light was off immediately and has not shown up so far.

High on the computer printout of a P1130 read at my local AutoZone shop, (exhaust) vacuum leak is the second item on the list, before AF sensor heater circuit (3) and AF sensor failure (4). The first entry in the "probable cause" section is "fuel pump, injector or pressure regulator fault".

RichardT

It is a different shape than the original. Its all boxy and fits the housing perfectly though. The original on the other hand had a little flap on all sides. I did find out later that I did not replace the cover properly. After proper placement and driving about 20 miles, the CEL came back. Codes are PO171 and P1130. I have already replaced the MAF sensor and just placed an order for denso front and rear O2 senors. My RX300 has 160,000 miles. I am at a 152 miles on half tank of gas with city and highway driving as of right now (which I think is fantastic). Smell gas when I initially start the vehicle in the morning. Have also replaced Transmission fluid and filter and have a new gas cap.

RichardT

Finally got the O2 sensor replaced at the catalytic converter. That did the trick and P1130 is off my diagnostics.

mikep415

^^ same thing is happening to my GF's car. I'll need to order that sensor as well.

Brohamm1

Just had this code pop up today, pulled the code, went inside to watch the game and nod. Got up wnet to the gas station for a paper and fillup. When I replaced the gas cap - the code was gone ? I have no idea if the error was a losse gas cap or not. Just wondering?

Lexmex

Welcome to the Club.

When the gas tank is low, you might be getting a lit of the crud at the bottom of the tank going through the combustion and/or the pressure (depending on how low), may not be the same because gas can sputter in there at that point. You get more air than fuel (or fuel+crud) and that ratio gets out of whack and you get a check engine light.