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insite

P1117 and P1121 on NEW O2 Sensors

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does anyone know if all four O2 sensors have heating actuated by the same relay, or is it two different relays?

There is just one relay (in the trunk behind the panel on the driver's side) and it also controls the fuel injectors and something else. If it were the relay, I would think the injectors wouldn't work either. There are also 4 separate circuits for each O2 sensor. In any case, at one point I swapped the relay with another identical one in the panel to make sure that wasn't it.

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does anyone know if all four O2 sensors have heating actuated by the same relay, or is it two different relays?

There is just one relay (in the trunk behind the panel on the driver's side) and it also controls the fuel injectors and something else. If it were the relay, I would think the injectors wouldn't work either. There are also 4 separate circuits for each O2 sensor. In any case, at one point I swapped the relay with another identical one in the panel to make sure that wasn't it.

thanks; my book identified the #2 relay in the trunk as EFI / primary O2 sensors but didn't spec the secondary O2 sensors. the thing's only like $13; i'll just replace it and see what happens.

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check the heating circuit with a volt meter. There should be 12v on the heater lead at the O sensor. what does the book say about checking the front O2 heater circuit? It is probably the same for the rear.

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check the heating circuit with a volt meter. There should be 12v on the heater lead at the O sensor. what does the book say about checking the front O2 heater circuit? It is probably the same for the rear.

it's getting voltage and the impedance of the sensor heaters is fine. what i haven't done is to check the voltage at the relay or DME.

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I just took my car for a test drive and got the codes within minutes. It's like it's worsening. Ugh. FWIW, I also checked voltage at the DME and it seemed to behave fine. At start up, got 12 v constant but once hot it seemed to just send a short test signal. Based on this, at least in my case, I don't think it's the heater itself.

Edited by heyjae

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I just took my car for a test drive and got the codes within minutes. It's like it's worsening. Ugh. FWIW, I also checked voltage at the DME and it seemed to behave fine. At start up, got 12 v constant but once hot it seemed to just send a short test signal. Based on this, at least in my case, I don't think it's the heater itself.

that's the way it's supposed to work. the DME actuates the relay at startup since this is when heating needs to occur. after the car is warm, there is no need to heat the sensors as this occurs from the exhaust stream; the heaters are disabled at this point, so DME output should be 0V.

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I just took my car for a test drive and got the codes within minutes. It's like it's worsening. Ugh. FWIW, I also checked voltage at the DME and it seemed to behave fine. At start up, got 12 v constant but once hot it seemed to just send a short test signal. Based on this, at least in my case, I don't think it's the heater itself.

that's the way it's supposed to work. the DME actuates the relay at startup since this is when heating needs to occur. after the car is warm, there is no need to heat the sensors as this occurs from the exhaust stream; the heaters are disabled at this point, so DME output should be 0V.

I know. That is what's frustrating-everything seems to be working fine, but I get these CELs. I'm really interested in what you find.

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this is mysterious. if you followed the heater circuit procedure for the front and got nowhere, and there is no procedure for the rear codes, I would go back to square one and run the overall DME diagnostic performance checks in the book, if there are any.

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insite,

Any updates on your CELs? I have been able to eliminate my P1117 by simply cleaning the contacts and using a jewelers screwdriver to push the contacts closer together within the harness. So far it seems to have done the trick. I'm still getting a P1115 even though I did the same with that sensor. I have to do more testing on that one. It may be out of spec.

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insite,

Any updates on your CELs? I have been able to eliminate my P1117 by simply cleaning the contacts and using a jewelers screwdriver to push the contacts closer together within the harness. So far it seems to have done the trick. I'm still getting a P1115 even though I did the same with that sensor. I have to do more testing on that one. It may be out of spec.

actually i did find the problem. one of the new O2 sensors was intermittantly showing open loop on the heater circuit. i measured them two weeks ago; they were fine. i measured them again on wednesday while i was swapping out my tranny; one of them showed OL. paragon is sending me a replacement. that SHOULD fix it; well see.

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insite,

Any updates on your CELs? I have been able to eliminate my P1117 by simply cleaning the contacts and using a jewelers screwdriver to push the contacts closer together within the harness. So far it seems to have done the trick. I'm still getting a P1115 even though I did the same with that sensor. I have to do more testing on that one. It may be out of spec.

actually i did find the problem. one of the new O2 sensors was intermittantly showing open loop on the heater circuit. i measured them two weeks ago; they were fine. i measured them again on wednesday while i was swapping out my tranny; one of them showed OL. paragon is sending me a replacement. that SHOULD fix it; well see.

Any updates?

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I am having the same problem with the P1117 code, and all my 4 o2 sensors are new. Iam gona swap the o2 relay and see what happens.

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I am having the same problem with the P1117 code, and all my 4 o2 sensors are new. Iam gona swap the o2 relay and see what happens.

Chances are you have an open or shorted wiring harness.

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I replaced all 4 of mine over a year ago and got the same codes. It came on while engine was warm and at freeway speed and eventually after several drive cycles the light would go out. The time between CEL's gradually increased and when it came on it would gradually go out after fewer and fewer drive cycles. Eventually CEL went out and stayed out and I haven't had one in over 3 months and over 3,000 miles.

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I am having the same problem with the P1117 code, and all my 4 o2 sensors are new. Iam gona swap the o2 relay and see what happens.

Chances are you have an open or shorted wiring harness.

I swap the relays, but guys if the relay is bad the car won't start(it also work the ignition coils). I will follow the hardness from the DME foropen or shorts next week(not this one because I dislocate my knee cap). I will keep you informed.

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I am having the same problem with the P1117 code, and all my 4 o2 sensors are new. Iam gona swap the o2 relay and see what happens.

Chances are you have an open or shorted wiring harness.

I swap the relays, but guys if the relay is bad the car won't start(it also work the ignition coils). I will follow the hardness from the DME foropen or shorts next week(not this one because I dislocate my knee cap). I will keep you informed.

Now I'm getting P1115 as well.

Going to play with some resistor this weekend, also i notice that pin 1,2 only send 9.75volts.

Has anyone ground pin 1?

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I replaced all 4 of mine over a year ago and got the same codes. It came on while engine was warm and at freeway speed and eventually after several drive cycles the light would go out. The time between CEL's gradually increased and when it came on it would gradually go out after fewer and fewer drive cycles. Eventually CEL went out and stayed out and I haven't had one in over 3 months and over 3,000 miles.

4 months and counting!

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I replaced all 4 of mine over a year ago and got the same codes. It came on while engine was warm and at freeway speed and eventually after several drive cycles the light would go out. The time between CEL's gradually increased and when it came on it would gradually go out after fewer and fewer drive cycles. Eventually CEL went out and stayed out and I haven't had one in over 3 months and over 3,000 miles.

4 months and counting!

I wish!!!

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If the car is running OK other than the CEL, let it go and see if engine computer doesn't adapt.

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Sorry to revive this 4 year old thread. Is there a definite solution?

1. Is the consensus to just wait it out?

2. Relay issue? Kind of strange if it was working before change and right after the relay goes.

3. Bosch has quality control issues ? or using a different heater circuit?

I had only P1121 code, so I decided to replace both the rear O2 sensors NOT universal.

I drove about 40 miles with several stops. While driving around 60mph and the cars all warmed up I get P1117 and P1121. Similar as what happened to you guys. I was under the impression that the Heater circuit comes on when the car is cold and not when its hot and running at high speed?

Thanks

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Sorry to revive this 4 year old thread. Is there a definite solution?

1. Is the consensus to just wait it out?

2. Relay issue? Kind of strange if it was working before change and right after the relay goes.

3. Bosch has quality control issues ? or using a different heater circuit?

I had only P1121 code, so I decided to replace both the rear O2 sensors NOT universal.

I drove about 40 miles with several stops. While driving around 60mph and the cars all warmed up I get P1117 and P1121. Similar as what happened to you guys. I was under the impression that the Heater circuit comes on when the car is cold and not when its hot and running at high speed?

Thanks

O2 sensors are easy to test - see my earlier posts (in this thread).

P1121 is a throttle position fault.

Not really related unless the throttle is not closing when the DME tells it to.

Try cleaning your electrical contacts on the throttle position sensor (electrical contact cleaner only) - and - clean your throttle body with spray throttle body cleaners.

Clear the codes and see if they come back.

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