Air / Fuel Sensor

[michaelamiller]

I have a 2001 Lexus ES300 with both the Check Engine Light and Trac Light on. AutoZone analysis showed code P1135 Air/Fuel sensor heater circuit malfunction. I replaced the oxygen sensor, Bank 1, Senor 1, by the radiator easily. That did not solve the problem. I tried to replace, Bank 1, Senor 2, between the firewall and engine, on the exhaust manifold. That sensor was frozen in place, seized, and could not be removed.

I went to the Lexus dealer initially and they wanted $ 162. for analysis, $ 214. for the part, and $ 216. for labor. I have 80,800 miles on the car.

Please tell me how you think I should proceed?

Thanks,

Michael A. Miller

[George_Jetson]

Bank 1 is next to the firewall, bank 2 is next to the radiator. Sensor 1 is located near the cylinder head, sensor 2 is further back, behind the cat converter ( it monitors cat operation).

Now as far as the error code. Many people make this mistake. They read the ccde and automatically start replacing parts. This is a very expensive method of approching the problem. You need to make check the system out before throwing parts at the car. In this case you have a heater sensor circuit malfunction. The sensor has a heater built into it. One side of the heater is connected (thru a fuse) to a switched 12 volt supply. The other side of the heater is connected to the ECM. The ECM completes the circuit, IE it supplies a grd. The ECM also monitors the current thru this grd. If the current is not in spec the ECM generates a code for a heater circuit malfunction.

So as this point we need to check several things. The first step should have been to check the fuse. The next step is to check the switched voltage source. Then measure the resistance of the 02 sensor. Finally you need to verify that the ECM is suppling a grd. The last step would be to replace the ECM.

So at this point I would first check the fuse. Then you could pick one of the other steps, such as measure the resistance of the heater, or check the switched voltage source. And then maybe checking the ECM input. Since you are having issuses replacing the sensor you would want to try and eliminate other possible problems. Or you could go right to measuring the resistance of the sensors.

Lastly, taking the car to a Lexus dealer is the most expensive way to get the car replaced. Any independent garage can easily replace the sensor for a fraction of what you would pay a dealer.

[camlex]

hope you saved first replaced oxygen sensor, Bank 1 and bank 2 are same. now replaced as george say by firewall.

[michaelamiller]

Bank 1 is next to the firewall, bank 2 is next to the radiator. Sensor 1 is located near the cylinder head, sensor 2 is further back, behind the cat converter ( it monitors cat operation).

Now as far as the error code. Many people make this mistake. They read the ccde and automatically start replacing parts. This is a very expensive method of approching the problem. You need to make check the system out before throwing parts at the car. In this case you have a heater sensor circuit malfunction. The sensor has a heater built into it. One side of the heater is connected (thru a fuse) to a switched 12 volt supply. The other side of the heater is connected to the ECM. The ECM completes the circuit, IE it supplies a grd. The ECM also monitors the current thru this grd. If the current is not in spec the ECM generates a code for a heater circuit malfunction.

So as this point we need to check several things. The first step should have been to check the fuse. The next step is to check the switched voltage source. Then measure the resistance of the 02 sensor. Finally you need to verify that the ECM is suppling a grd. The last step would be to replace the ECM.

So at this point I would first check the fuse. Then you could pick one of the other steps, such as measure the resistance of the heater, or check the switched voltage source. And then maybe checking the ECM input. Since you are having issuses replacing the sensor you would want to try and eliminate other possible problems. Or you could go right to measuring the resistance of the sensors.

Lastly, taking the car to a Lexus dealer is the most expensive way to get the car replaced. Any independent garage can easily replace the sensor for a fraction of what you would pay a dealer.

[michaelamiller]

hope you saved first replaced oxigen sensor, Bank 1 and bank 2 are same. now replaced as george say by firewall.

Dear Camlex,

First I checked the fuse, it was OK. Them I removed the two sensors I could and checked to see if the heater was open circuited, ohm meter. Both were OK. Since I could easily remove one and the code indicated that was a possibility, I replaced it, keeping the old part. When this didn't solve the problem, I disconnected the one I could not remove and just plugged in the good one, this solved the problem. I now knew that here heater in this unit was bad. Now I must determine the best way to remove it. Any suggestions that might help? I agree that the dealer is very pricy. The first independent garage I took it too gave me an undetermined estimate after that said it was frozen in place, sized. I have tried different products like WD-40 with no luck so far. Any suggestions?

Thanks,

Michael A. Miller

[lenore]

Heat will allow it to be removed. Hitting it with a torch and then wrenching it. I know a very scarey prospect.

[George_Jetson]

If it is frozen you really do not have many choices. Take it back to the independent shop and have them remove it. Before you take it down, I would first call around and get prices for a rear manifold. It helps to know how much money to spend on trying to remove the old sensor, or replace the manifold. Either way when the sensor is frozen in place it is best to lift the car and use a torch to remove the sensor.

[michaelamiller]

If it is frozen you really do not have many choices. Take it back to the independent shop and have them remove it. Before you take it down, I would first call around and get prices for a rear manifold. It helps to know how much money to spend on trying to remove the old sensor, or replace the manifold. Either way when the sensor is frozen in place it is best to lift the car and use a torch to remove the sensor.

It is difficult to find an independent shop that will give a quote other then we'll see once with get to the manifold. I did find one recommended by a friend who indicated that he had done this before and the price was $ 175. based on removing the manifold drilling out the sensor and retapping the hole. This at least puts a lid on the operation. I have an appointment for tomorrow at 9 AM. We'll see what the outcome is. I would imagine that this is a routine service operation; but this is my first experience with this type of replacement. Couldn't Lexus find a better place for the sensor?

Thanks very much for your advice and counsel.

Michael A. Miller

[George_Jetson]

I could understand most shops would be hesitent to give a qoute, hard to tell exactly how long it would take to do this job. As far as the sensor location, they really do not have very many options. Due to emision regulations, auto manufactures must locate a set of cats as close to the cyl head has possible (so that they come up to operating temp as quickly as possible). Since the first O2 sensors monitor mixture, they must be located before the cats. All OBDII cars are like this.

I would suggest taking a close look at the Y pipe. If the flex connections are starting to look bad you may want to consider replacing them at this time. They will have to disconnect part of the y pipe to replace the manifold, so you should save some of the labor costs.

[michaelamiller]

I could understand most shops would be hesitent to give a qoute, hard to tell exactly how long it would take to do this job. As far as the sensor location, they really do not have very many options. Due to emision regulations, auto manufactures must locate a set of cats as close to the cyl head has possible (so that they come up to operating temp as quickly as possible). Since the first O2 sensors monitor mixture, they must be located before the cats. All OBDII cars are like this.

I would suggest taking a close look at the Y pipe. If the flex connections are starting to look bad you may want to consider replacing them at this time. They will have to disconnect part of the y pipe to replace the manifold, so you should save some of the labor costs.

Dear George Jetson,

Thanks, I just check out the Y pipe and the flex connections look OK so I don't think they need to be replaced; but if the mechanic suggests this, I'll know what he means and act accordingly, i.e. replace them as this is beyond my expertise. Trusting the mechanic is a real problem based on past performace and this is a new shop I'm using. I think making the choice between replacing the manifold or drilling out the sensor is something the mechanic will have to do once the old manifold is removed and I don't want to second guess him as I will not be there nor will I have the expertise to make this call. I tried the heat and the hammer on the sensor, no luck, it is in really solid. I think I have done as much as possible with my limited knowledge and facilities.

Michael A. Miller

[michaelamiller]

I could understand most shops would be hesitent to give a qoute, hard to tell exactly how long it would take to do this job. As far as the sensor location, they really do not have very many options. Due to emision regulations, auto manufactures must locate a set of cats as close to the cyl head has possible (so that they come up to operating temp as quickly as possible). Since the first O2 sensors monitor mixture, they must be located before the cats. All OBDII cars are like this.

I would suggest taking a close look at the Y pipe. If the flex connections are starting to look bad you may want to consider replacing them at this time. They will have to disconnect part of the y pipe to replace the manifold, so you should save some of the labor costs.

Dear George Jetson,

Thanks, I just check out the Y pipe and the flex connections look OK so I don't think they need to be replaced; but if the mechanic suggests this, I'll know what he means and act accordingly, i.e. replace them as this is beyond my expertise. Trusting the mechanic is a real problem based on past performace and this is a new shop I'm using. I think making the choice between replacing the manifold or drilling out the sensor is something the mechanic will have to do once the old manifold is removed and I don't want to second guess him as I will not be there nor will I have the expertise to make this call. I tried the heat and the hammer on the sensor, no luck, it is in really solid. I think I have done as much as possible with my limited knowledge and facilities.

Michael A. Miller

[flanso]

I ran into a stuck bank 1 sensor 1 on my 2001 ES300. I resolved it by first removing the short tubular brace that goes between the intake and engine to get more working room. I sprayed the sensor with penetrating solvent and let it sit for a couple of hours. Then I disconnected the sensor wire and threaded it through a long handled Snap-On 7/8 inch box end wrench until the wrench was squarely over the sensor's hex. The bit of extra room along with the box end on the sensor plus a pair of gloves gave me the confidence to really exert some force on the end of that wrench until the thing finally broke loose.