I have a question about a check-engine light code. I have a 2004 Camry 4 cylinder with about 75k miles.

I have had sporadic intervals where the check engine comes on, and after one or at most two driving sessions goes back off. The intervals between check engine light occurrences range from one week apart to several months. At first I thought it may have been the gas cap. I had the code read and it was a P2238. According to the info I looked up it has this definition.

Oxygen sensor or A/F ratio sensor circuit low - bank sensor 1

Probable causes
- Open or short circuit condition
- Poor electrical connection
- Failed A/F sensor
- Fuel pressure, vacuum leak, MAF sensor fault

I've talked to a couple of mechanics and they suggest replacing the O2 sensors. I don't think the car is old enough to have wiring problems, so I believe that they probably should be replaced. The only thing that bugs me is that I don't have the severe symptoms of a failed O2 sensor, like poor acceleration or worse gas mileage. I'm willing to accept that the sensor may be on the way out, but I don't know enough to know how serious the problem is. I can wait it out for more severe symptoms, but that may be a bad idea.

If I need to replace the O2 sensor, I have a couple questions.

Is it recommended that I get specifically a Toyota brand part, or can I get any name brand?

Should I replace both O2 sensors at the same time, since the lifetime may be an issue for the other ones? What is the expected lifetime for O2 sensors?

Which O2 sensor is this code referring to? I think it's the one upstream of the catalytic converter, but I don't know which one, or maybe both of them. I'm ordering a camry manual to try to get more educated.

Thanks for any responses.
John D.

 

The A/F sensor is Bank 1, Sensor 1. This is first sensor on the exhaust system starting out from the cylinder head. The upstream sensor.

Typically the sensor should last longer then this. EPA and some states mandate a separate warranty on these sensors but it most likely has expired. These sensors do fail.

Some issues are the car may be emitting higher emissions and this will show up during an emissions test. The check engine light being on at the time of testing will result in automatic failure of the test. A failing sensor can cause the fuel/air ratio to run rich resulting in the potential for increased catalytic converter failure.

If replacing the sensor recommend either Toyota brand or Denso. Others sensors are available but on occasion their use on Toyota products results in the check light coming back on. If using Denso, get the sensor that is specific for the Make, Model and year of car, not a "universal" type sensor.

If handy with tools you should be able to do the job your self. The Autozone website has a very good self help repair section or do a Google search on replacing the A/F sensor for this engine.

You can get cheaper after parts at websites like Rockauto. For discount Toyota parts try www.1sttoyotaparts.com or Toyota of Dallas.

Might also do a Google search on this code and Camry. Determine if there are any other issues out there. Sometimes Toyota has a service bulletin out on recurring problems and what is the fix. The cause could be something not related to typical issues outlined in the manual.

 

Thanks for your information. I also did a bit more google searching and found at one site where someone said that there is a technical service bulletin EG034-04 that looks at replacing the air-fuel ratio sensor and recalibrating the engine control unit.

Is there a site that one can look these things up to verify if the information is valid? Are these things typically covered under factory warranty?

 

I found something at alldatadiy that matched the EG034R-04 number, but can't get a detailed description.

 

See link below:

http://en.allexperts.com/q/Toyota-Re...Highlander.htm

Mentions the EG034-04 applies to Camry.

From what can remember this was a sensor change and a re-flash of the computer.

A dealer has access to all TSB's. As stated in the link Toyota typically extends the warranty to cover issues such as this, if the car is covered there should be no cost to you.

Might also post at the Toyotanation website where members are more up to speed.

On TSB's action, the customer typically needs to take action (complain) about a problem. The dealer typically will not "volunteer" the info (as directed by Toyota).

Suggest you visit a dealer, ask about this TSB and if it applies to your car.

 

I looked up the warranty on the federal emissions and it appears that it says that it is covered for 3 yr / 36k miles, but some parts are covered for 8 yr/ 80k miles. The A/F sensor is not specifically labeled under the 8/80, so I don't think it's covered unless its one of those specific covered parts (ECU, catalytic converter, ...).

Do you recommend just replacing the A/F sensor that is triggering the sporadic P2238 check-engine light codes and see if the codes go away, or have a full emissions system diagnostic?

Edit: I do plan on taking it to the dealer and asking them to explain the details. I'm just wondering if I should look for a full diagnostic or just get the sensor replaced and see what happens?

Thanks again,
John D.

 

You need to find out what the TSB states and if it applies to your car.

In cases of defective parts, computer re-flash, etc Toyota has extended the warranty for repairs beyond the typical 36k/36M or the EPA 80k/80M.

The warranty period extension would be stated in the TSB EG034-04.

Suggest you first approach the dealer and ask about this TSB and if it applies to your car. If it does and the car is still under any extended warranty for this repair as provided by the TSB the dealer should repair the car at no charge.