Check Engine Light

[apatrules]

In more than 8 years owning the 2000 GS 400, the "Check Engine" light never appeared. In September, while driving

through a severe rain storm, the light came on. The next morning when I started the car, the light was still on. I checked

the gas cap and it was on tight. Drove the care nearly 300 miles and when I stopped the engine and re-started the light was

no longer on.

The dealer said the engine computer did not record anything related to the check engine light and since the light was no

longer on, they could not tell me what might have gone wrong.

No problems for two months and then it happened again in the same place (New Jersey) and this time, the light went out when I shut the car off after driving the next day in the dry weather for 175 miles.

No performance degradation when the light is on. Any thoughts on why the light would go on in heavy rain. Note: I did not drive through any large puddles that would have flooded the engine compartment.

Thanks, in advance, for any ideas.

[GS400&aGSXR750]

When my check engine light came on, I took it to Advance Auto or Pep Boys and used there free hand held computer diagnostic test set and it told me the code was for the oxygen sensor. I went to two mechanics and asked them about my check engine light, and the first thing both of them said was, it's probably my oxygen senssors. You might want to see if you can have the code read when it or if it occurs again from the auto parts store.

[apatrules]

When my check engine light came on, I took it to Advance Auto or Pep Boys and used there free hand held computer diagnostic test set and it told me the code was for the oxygen sensor. I went to two mechanics and asked them about my check engine light, and the first thing both of them said was, it's probably my oxygen senssors. You might want to see if you can have the code read when it or if it occurs again from the auto parts store.

Thanks. That is a helpful suggestion I will try. Do you know if the light has to remain on for the computer to give a read out of the problem?

Also wonder why the oxygen sensor would be an issue when the car is driven in heavy rain.

Will check it out. Thanks again.

[Lexus GS430 Guzzler]

When my check engine light came on, I took it to Advance Auto or Pep Boys and used there free hand held computer diagnostic test set and it told me the code was for the oxygen sensor. I went to two mechanics and asked them about my check engine light, and the first thing both of them said was, it's probably my oxygen senssors. You might want to see if you can have the code read when it or if it occurs again from the auto parts store.

Thanks. That is a helpful suggestion I will try. Do you know if the light has to remain on for the computer to give a read out of the problem?

Also wonder why the oxygen sensor would be an issue when the car is driven in heavy rain.

Will check it out. Thanks again.

O2 sensor problems, even minor ones can have the weirdest effects on an engine.

Always put in an OEM O2 sensor. Just about anything else on a Japanese car can be aftermarket. I've learned the hard way that OEM O2 filter is always the way to go.

[apatrules]

When my check engine light came on, I took it to Advance Auto or Pep Boys and used there free hand held computer diagnostic test set and it told me the code was for the oxygen sensor. I went to two mechanics and asked them about my check engine light, and the first thing both of them said was, it's probably my oxygen senssors. You might want to see if you can have the code read when it or if it occurs again from the auto parts store.

Thanks. That is a helpful suggestion I will try. Do you know if the light has to remain on for the computer to give a read out of the problem?

Also wonder why the oxygen sensor would be an issue when the car is driven in heavy rain.

Will check it out. Thanks again.

O2 sensor problems, even minor ones can have the weirdest effects on an engine.

Always put in an OEM O2 sensor. Just about anything else on a Japanese car can be aftermarket. I've learned the hard way that OEM O2 filter is always the way to go.

Thanks. Will get it checked next week andlet you know the results.

[apatrules]

When my check engine light came on, I took it to Advance Auto or Pep Boys and used there free hand held computer diagnostic test set and it told me the code was for the oxygen sensor. I went to two mechanics and asked them about my check engine light, and the first thing both of them said was, it's probably my oxygen senssors. You might want to see if you can have the code read when it or if it occurs again from the auto parts store.

Thanks. That is a helpful suggestion I will try. Do you know if the light has to remain on for the computer to give a read out of the problem?

Also wonder why the oxygen sensor would be an issue when the car is driven in heavy rain.

Will check it out. Thanks again.

O2 sensor problems, even minor ones can have the weirdest effects on an engine.

Always put in an OEM O2 sensor. Just about anything else on a Japanese car can be aftermarket. I've learned the hard way that OEM O2 filter is always the way to go.

Thanks. Will get it checked next week andlet you know the results.

Brought the car to the dealer who says the computer readout is PO 430--Low Catalytic Converter Efficiency. Of course, suggests

replacing Cat Converter for $1500. My unanswered question: If the efficiency of the cat conveter is low, why is it low and light comes on only in certain circumstances--ie heavy rain? And then when the rain ends and car is driven the light goes out.

Two questions: 1. How could rain negatively impact the catalytic converters and is there anything that can be done to alleviate this issue without replacing the cats?

2. As earlier indicated, the check engine light never came on in first 120,000 miles of driving. At 120,000 I reluctantly had the spark plugs replaced for the first time (as recommended by the book). And now I have gotten this check engine reading twice in heavy rain. Any chance there is a relation between new plugs and how they were installed and the check engine light?

Thanks.

[SRK]

The O2 sensor suggestion is a good one. Rain can affect both the sensor and the cats. First, if water enters the sensor's reference air port, it will plug it briefly - off road guys do this to the sensors on their 4x4's, but with mud. On some cars leaky valve covers will put oil on the sensor. Oil and mud don't clear themselves, but water will. For the cat, water immersion or heavy rain will cool the cat down enough that the post cat sensors will believe the cat is not functioning correctly. When everything dries out and the temp comes up, all is well.

The fact that you have noticed that it only happens in heavy rain tells me everything is OK.

[sakataj]

No problems for two months and then it happened again in the same place (New Jersey) and this time, the light went out when I shut the car off after driving the next day in the dry weather for 175 miles.

maybe your car doesnt like jersey and is just telling you to stay away from there......... B)