Code P1150 After Alternator Replacement

[unccs]

Dear Experts,

My 2000 Lexus RX300 has only 93K. I replaced the alternator with OEM part in an independent shop that specializes in BMW but also do some Lexus work. The alternator was making noises and the noise was gone after the replacement. However, my engine light is on with code P1150 the day after the alternator is replaced. The code means front bank air/fuel ratio sensor needs to be replaced. Today(two days after the alternator work) the engine light is off. How often is this code rechecked? Do I expect it to come on and off? Can I drive this car for a 600 miles trip tomorrow? If the sensor is indeed bad, will the engine be damaged if I keep driving it for short or long distance?

Could it possibly be related to the alternator work that was just completed? They quoted me $275 to have the sensor replaced but I'm not sure I can still trust them.

The shop did touch the air filter as they told me it needs to be replaced. I examined the air filter after wards but has not yet replaced it. Could it be possible that my repositioning of the air filter actually fixed the problem since the engine check light went off not long after I touched the air filter?

Thanks for any help in advance.

Jason

[Filehorse]

I'd be taking a close look at all the connectors/wiring for the O2 sensors - especially the one nearest the radiator. Can't think of any electrical reason for there to be a relationship between the alternator repair and a code for a failed O2 sensor. A roundup of the usual suspects would include something happening to the sensor wiring during the removal/install of the alternator. Hopefully it'll be something obvious.

[joe913]

I'd be taking a close look at all the connectors/wiring for the O2 sensors - especially the one nearest the radiator. Can't think of any electrical reason for there to be a relationship between the alternator repair and a code for a failed O2 sensor. A roundup of the usual suspects would include something happening to the sensor wiring during the removal/install of the alternator. Hopefully it'll be something obvious.

P1150 Air/Fuel Ratio Sensor Circuit Range/Performance Malfunction (Bank 2 Sensor 1)

Not O2! This is the sensor that is on the exhaust manifold between the engine and the radiator. If you follow the wires, they will take you to a connecter on the right side (as you are looking at it from the front of the car) of the engine, just above the transmission. The connector may have been disconnected by mistake or accident. However, it is on the other end of the engine from the alternator. If you know how to operate an ohm meter, there is an instructional document that will be helpful in troubleshooting. It is too large for uploading to this site (3.7MB). If you PM your email address, I will send the document. It will walk you through the testing procedure. Good luck.

[Filehorse]

I'd be taking a close look at all the connectors/wiring for the O2 sensors - especially the one nearest the radiator. Can't think of any electrical reason for there to be a relationship between the alternator repair and a code for a failed O2 sensor. A roundup of the usual suspects would include something happening to the sensor wiring during the removal/install of the alternator. Hopefully it'll be something obvious.

P1150 Air/Fuel Ratio Sensor Circuit Range/Performance Malfunction (Bank 2 Sensor 1)

Not O2! This is the sensor that is on the exhaust manifold between the engine and the radiator. If you follow the wires, they will take you to a connecter on the right side (as you are looking at it from the front of the car) of the engine, just above the transmission. The connector may have been disconnected by mistake or accident. However, it is on the other end of the engine from the alternator. If you know how to operate an ohm meter, there is an instructional document that will be helpful in troubleshooting. It is too large for uploading to this site (3.7MB). If you PM your email address, I will send the document. It will walk you through the testing procedure. Good luck.

My bad. Another case of writing an answer to a question that wasn't asked. I'll wait until the coffee kicks in next time.

[joe913]

I'd be taking a close look at all the connectors/wiring for the O2 sensors - especially the one nearest the radiator. Can't think of any electrical reason for there to be a relationship between the alternator repair and a code for a failed O2 sensor. A roundup of the usual suspects would include something happening to the sensor wiring during the removal/install of the alternator. Hopefully it'll be something obvious.

P1150 Air/Fuel Ratio Sensor Circuit Range/Performance Malfunction (Bank 2 Sensor 1)

Not O2! This is the sensor that is on the exhaust manifold between the engine and the radiator. If you follow the wires, they will take you to a connecter on the right side (as you are looking at it from the front of the car) of the engine, just above the transmission. The connector may have been disconnected by mistake or accident. However, it is on the other end of the engine from the alternator. If you know how to operate an ohm meter, there is an instructional document that will be helpful in troubleshooting. It is too large for uploading to this site (3.7MB). If you PM your email address, I will send the document. It will walk you through the testing procedure. Good luck.

My bad. Another case of writing an answer to a question that wasn't asked. I'll wait until the coffee kicks in next time.

Sorry,

I replied to the wrong note by mistake. My answer was directed to the originator of the topic. My mistake!

[code58]

Jason- They could have (but probably didn't) disturb the sensor wiring during replacement of the alternator. Modern electronics are very fickle and can drive you nuts sometimes. My suggestion- ANY TIME you have electronic gremlins, the 1st thing to do is "reset" the plug (or fuse). Unplug and replug it 3-5 times. That will clean the oxidization off and very possibly clear your problem. Doesn't have to look dirty to lose contact! My guess is that is what is going on.

[unccs]

Many thanks to everyone for your help. In my original post, I mistakenly said o2 sensor was bad. I've edited the post.

Jason

[unccs]

Jason- They could have (but probably didn't) disturb the sensor wiring during replacement of the alternator. Modern electronics are very fickle and can drive you nuts sometimes. My suggestion- ANY TIME you have electronic gremlins, the 1st thing to do is "reset" the plug (or fuse). Unplug and replug it 3-5 times. That will clean the oxidization off and very possibly clear your problem. Doesn't have to look dirty to lose contact! My guess is that is what is going on.

Thanks. Can you please elaborate where to find and how to reset the plug? I'm novice but eager to learn. BTW, the ECL has not come on for two days.

[code58]

Jason- They could have (but probably didn't) disturb the sensor wiring during replacement of the alternator. Modern electronics are very fickle and can drive you nuts sometimes. My suggestion- ANY TIME you have electronic gremlins, the 1st thing to do is "reset" the plug (or fuse). Unplug and replug it 3-5 times. That will clean the oxidization off and very possibly clear your problem. Doesn't have to look dirty to lose contact! My guess is that is what is going on.

Thanks. Can you please elaborate where to find and how to reset the plug? I'm novice but eager to learn. BTW, the ECL has not come on for two days.

Jason- When you open the hood look straight down on the front exhaust. You will find what looks like a spark plug with a 4 wire lead on it and a plug at the end of that lead. That is your front A/F ratio sensor. (the one that triggered the P1150 code) Refer to my last post as to how to "reset" the plug. The plug I'm referring to is the plug on the end of that 4 wire lead.

[unccs]

Jason- They could have (but probably didn't) disturb the sensor wiring during replacement of the alternator. Modern electronics are very fickle and can drive you nuts sometimes. My suggestion- ANY TIME you have electronic gremlins, the 1st thing to do is "reset" the plug (or fuse). Unplug and replug it 3-5 times. That will clean the oxidization off and very possibly clear your problem. Doesn't have to look dirty to lose contact! My guess is that is what is going on.

Thanks. Can you please elaborate where to find and how to reset the plug? I'm novice but eager to learn. BTW, the ECL has not come on for two days.

Jason- When you open the hood look straight down on the front exhaust. You will find what looks like a spark plug with a 4 wire lead on it and a plug at the end of that lead. That is your front A/F ratio sensor. (the one that triggered the P1150 code) Refer to my last post as to how to "reset" the plug. The plug I'm referring to is the plug on the end of that 4 wire lead.

Thank you for your help. The CEL is off for 2 weeks now.