Blowing smoke, tailpipe 1999 Nissan Maxima

I have a 1999 Nissan Maxima that I am going to pass on to my soon to be 16 year old daughter. Her sister had it when she was 17-18 after I used it for several years. It has 240,000 miles, is in excellent condition and has had many of the vital components of the vehicle replaced. It now suddenly has started blowing a whitish smoke from the tailpipe. It has a very strong fuel smell while at idle or at a stop light or sign. It losses no oil, or coolant. The service engine light came on at the same time roughly that this smoke showed up. Under diag. hook-up it says bad o2 sensor. Should I assume that replacing the o2 sensor will solve this issue? If so, is that something I could do? I read online how to do it and it seems rather simple.

The O2 sensor will not solve the “whiteish smoke” problem. It’s sounds like you have one or more fuel injectors that are leaking or other fuel delivery problems. The service engine light is telling you there is a problem and the O2 sensor is a common reading. There are a myriad of other malfunctions that will make it seem like an O2 failure but only a good mechanic can sort that out for you. Finding the real malfunction will save you time and money so find a good independent mechanic.

You may have a “hung” injector…or one that cannot properly spray a mist of fuel…and instead dumps fuel into the engine. Unfortunately many things can cause this issue you are seeing…perhaps ALL the injectors are being “told” to spray additional fuel… Not sure how the enrichment circuit works on your Max I’d have to double check…but some cars have an extra injector that basically works like an old choke…if your car has one and it doesn’t shut off it will enrich your fuel mix way too much…I’d have to poke around for you about that…

If you have sorted it out far enough that you know its not a head gasket failure…By monitoring the coolant level and engine oil… That’s a good thing and a relief I’m sure…

So the smoke has a strong gas smell…yep…that’s unburned fuel. Many causes…you need to go to a good mechanic and not one that will take you on a wild ride suggesting every part under the sun for a 240K vehicle.

I wonder…guys could his MAF do this to him on this Max?

There are not codes that tell you that you have a bad O2 sensor. There are codes that report errors where the reports of errors come from an O2 sensor. Why would you assume a sensor is bad because it is doing its job? There are other codes that refer to O2 sensor circuit issues, but generally not that come with the symptoms you report.

Report the actual, specific code. Format: “P1234.” My guess is that it will point to rich running condition as missileman & HB are assuming. The O2 sensor could be at fault but it might also just be reporting on it. So post the code.

Wow, thank you everyone. I’ll have to see if I can get the codes and report back. In saying that it was a bad o2 sensor that is what was reported to me by the mechanic who did the diag., There was no charge and he suggested starting with the o2 as that is what was indicated by the reading. If that did not work then next possible fix might have to be fuel injector, if not that then start engine breakdown which he considered last resort and something another shop would have to do.

I’m not flush with money, in fact unemployed at the moment and this car has been a saving grace for me and my kids as they have come of age to drive. We are able here and there to do fixes to keep, as the girls call it “Black Beauty” alive, just hoping one more daughter may get to use it.

I’ll send the code as soon as I can…Thanks!!

Any shop mechanic WHO CARES…and knows his stuff will start diagnosing the issue as he should… He will read the codes and note them. Then see what is going on…the codes are sort of just clues and not part replacement instructions… The O2 sensor code can and will be thrown for many different reasons…That code could mean something is awry that made the Ecu throw an O2 code…but it is not always as simple as just swapping the sensor… SO let a good mechanic do what he is good at and have him search for root cause…

Cigroller also said all of this…and as usual with much fewer words…lol…I’m a bit loquacious most times…

There is NO NEED for engine teardown…until something tell the mechanic that he needs to tear it down to get to a certain item… Does that make sense? I just wish more places would actually DO THEIR JOB…and determine what is wrong rather than just throwing parts at it…There are clear cut ways to diagnosing an issue like this

Sorry for my delay in getting codes but now they do not exist. While the car still on occassion is blowing smoke and the smell of something, exhaust, fuel, ??? continues, and the service engine light is on codes seem to have disappeared.

My brother (first mistake) while intensions were good, hooked up his code reading device an OBII or something like that, and quickly erased the code with out writing it down. So…, I let the vehicle run for a couple of weeks with the same symptoms as before, the service light came on again and then re-ran the scan. Low and behold, no codes dedected. I’m sure it is the device which is (I can only assume) less advanced as the mechanics but it had read a code before bro managed to erase it, before writing it down.

Back to the mechanic I guess, just got a coupon for free engine diag. at a local mieneke, I’ll see what that does???

The white smoke might be from excess gas entering the engine from a leaking fuel pressure regulator. The fuel pressure regulator is located on the fuel rail for the injectors. It’s a small metal canister with a single vacuum hose connected to it. Remove the vacuum hose from the regulator, and if gas leaks out of this connection the regulator is leaking and requires replacement.


I’ll give that a try, thank you very much!! I assume you mean the gas will leak from the metal canister not the vaccum hose?