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Check Engine Light


daronson's Avatar
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03-11-04, 11:54 AM   #1  
Check Engine Light

Check Engine light came on a LONG time ago on my 2001 Nissan Maxima - currently has 85k miles, must've been about 78k or so when it first came on. Dealer said it wasn't a big deal, prob. has to do with the fuel cap not being fully tight before starting car after getting gas, or some BS like that.

Anyway, light went off after a month and a half, then came back on 1 week later. Same thing happened again - light eventually went off by itself.

This LAST time - 3 weeks ago, I was at the dealer for a 90K mile service (85k actual miles). I PAID $100 for the engine light to be diagnosed, another $100 for the O2 Sensor, Another $100 for labor to install O2 sensor, and ANOTHER $100 to "reprogram the computer".

$400 and 2 weeks later, the Service Engine light comes on....
After reading some posts, maybe it wasn't the sensor itself? Sounds like this was this the easy way out for the dealer. Also there are at least 2, maybe 3 TSB's on the O2 sensor for the '01 Maxima, but as you know ALLDATA doesn't give the details. If the O2 sensor is know to be problematic, why wouldn't they just replace it instead of charging me an extra $100 to diagnose that it is the O2 sensor.

This was a $1200 trip to the dealer on a car just over 3 years old for the following:

90k service($300)
engine light diagnosis ($400 )
engine oil flush ($100)
rear wheel bearing ($340 )
was making noise for a while, so I think this was justified

 
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03-11-04, 12:28 PM   #2  
So, why don't you just bring it back and complain to them instead of us. Sounds like they owe you at least some free diagnosis.

 
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03-11-04, 02:08 PM   #3  
Go to autozone and get the trouble codes and we will go from there.They do it free.

 
daronson's Avatar
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11-17-04, 11:19 AM   #4  
So I took the car back after a month or two and they agreed to diagnose the problem without charge, however, stated if it was NOT the O2 sensor, they would have to charge me.

Well, they told me it WAS the O2 sensor, but pulled the paperwork from the orignal repair and stated it was a DIFFERENT sensor. I asked how many there were, and he said FOUR!! He told me what prob. happened is that since the one sensor was bad, the others had to work harder to compensate and probably damaged the sensor in question. Not sure I buy that, but I told them not to bother replacing it.

So last week I took my car to get inspected, and they see the check engine light on, hook up the diagnostics and within 5 minutes tells me the trouble code (P0135), which equates to an O2 sensor. I then FAILED inspection. guess I DO need the O2 sensor replaced after all.

Is there an easier way to fix this problem other than shelling out $400 to the dealer? Any way to reset the engine light and get through inspection without replacing the sensor?

Thanks,

Dave

 
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11-17-04, 03:37 PM   #5  
It is a front O2 sensor and you can buy it for $105 and change it yourself.That will save you $295.You can't clear the code and pass an OBD2 emission test because all the monitors need to run to pass and clearing the codes resets the monitors to not run.So you need to replace the O2 sensor to pass.As I said 8 months ago Autozone can clear the code for free.

 
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11-17-04, 04:22 PM   #6  
Posted By: daronson \He told me what prob. happened is that since the one sensor was bad, the others had to work harder to compensate and probably damaged the sensor in question.
That makes no sense. The O2 sensors don't do any "work". They simply send voltage signals to the computer, based on the amount of oxygen in the exhaust.

I found this info on a web site about the P0135 code.

Description of code: During testing the HO2S Heaters are checked for opens/shorts and excessive current draw. The test fails when current draw exceeds a calibrated limit and/or an open or short is detected.

Possible causes:
Short to VPWR in harness or HO2S.
Water in harness connector.
Open VPWR circuit.
Open GND circuit.
Low battery voltage.
Corrosion or poor mating terminals and wiring
Damaged HO2S heater.
Damaged PCM.

This indicates that the problem is not necessarily the O2 sensor failing but could also be the wiring or something else in the computer-to-sensor circuit causing the fault. If the mechanic installed a new O2 sensor and the problem is still present, then obviously the problem lies elsewhere (barring a new bad sensor), meaning that you will again be charged for another diagnosis. I would assume, if you had 2 or more bad sensors when you brought the car to the dealer, they would have seen a different code for each bad sensor (i believe this is correct) but it sounds like they may have just assumed the sensor was bad and replaced it. $400 seems excessive to diagnose that if all he did was pull a code (which auto zone does for free) and replace the sensor. If you take the car back to the dealer, and he doesn't fix it for free, I'd try a different shop.


Posted By: daronson \they agreed to diagnose the problem without charge, however, stated if it was NOT the O2 sensor, they would have to charge me.
In other words "if we misdiagnosed the problem and charged you for it as well as the sensor, we'll charge you for a 2nd diagnosis"


To answer your question, the check engine light can be reset right before you go for an inspection but the inspectors computer may be able to see that you did that and not allow the car to pass. Someone else here may want to confirm that though because I'm not all that sure about how that works.

 
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11-17-04, 04:27 PM   #7  
Looks like davo answered your question while i was typing

 
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11-18-04, 08:47 AM   #8  
Davo - I understand if I bring the car back to be RE-INSPECTED, they will obviously run the diagnostics to make sure it is fixed, not just "reset".

Now, if I wait until after the 45 day period for RE-inspection and bring the car in for a FULL inspection, and the "check engine light" is NOT lit, will they STILL hook the car up to the diagnostics?? Now since everything is computerized, will they STILL know that I failed for O2 sensor last month?

I will look into replacing the sensor myself.

Jeff - thanks for you input as well. I think I can figure out how to replace the sensor (once I can physically FIND it under the hood) , but checking for all the other possible problems is a little beyond me. I guess I can just hope that the sensor is the problem and give it a shot.

$400 wasn't for just a diagnosis, it was $100 to diagnose, 100 for the part, 100 for labor and 100 to reset the computer. I agree with the $100 for the part, but NJ DMV just diagnosed it for free, I could save on the labor installing myself, and find an autozone (thanks DAVO) to reset the computer for free. What a RACKET!!!

The dealer basically said if they ran the diagnosis and it was the sensor they just replaced, they wouldn't charge me. Since the light came on so quickly after replacing the first sensor, the service manager agreed to NOT charge me for the diagnosis ($100).

 
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11-18-04, 02:00 PM   #9  
An emission test is an emission test 1st 2nd 3rd time it is always the complete test.If you clear the code the monitors need to run and pass,if the O2 sensor is not replaced the heater for the front O2 sensor will fail the monitor test and you will fail the emission test.It doesn't matter if it is an initial or retest you will fail.The light can be off and you can still fail the test because of the monitors that is why they went to the obd2 test.

 
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11-19-04, 07:26 AM   #10  
Thanks, that's exactly what I wanted to know. Regarding replacement, do you recommend Autozone to purchase the part, or could I just go to Pep boys?

Is there a website that shows the part locations so that I can easily find the O2 sensor that needs replacing? I am not even sure what I am looking for.

So after replacing, I can just go to Autozone and they will hook up and reset my computer for free???

 
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11-19-04, 09:25 AM   #11  
I would probably buy that sensor from the dealer....

 
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11-19-04, 02:23 PM   #12  
If you buy it from Auotzone after they read the code and if it's the wrong one(remember there are 4)they may exchange it for the proper one the dealer won't.I will get beat up for this but they sell Bosch O2 sensors and I never had problems with them when I worked at a non dealer shop.According to the website the one I think you need is the cheapest one out of the 4,around $55.I don't like Bosch spark plugs but if I remember correctly they invented the O2 sensor but it was called a Lamda sensor which is German for you guessed it oxygen.The dealer part is $105 where I found it on the net.Some other aftermarket sources are more than the Nissan part at $112 so you decide.

 
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11-21-04, 08:03 PM   #13  
Posted By: daronson
$400 wasn't for just a diagnosis, it was $100 to diagnose, 100 for the part, 100 for labor and 100 to reset the computer. I agree with the $100 for the part, but NJ DMV just diagnosed it for free, I could save on the labor installing myself, and find an autozone (thanks DAVO) to reset the computer for free. What a RACKET!!!
the DMV ran the "check engine" light diagnosis for free? Am I reading this correctly? wil DMVs in other states do this?

 
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11-22-04, 05:32 AM   #14  
The only reason DMV diagnosed the problem was so they could fail my car for inspection. They couldn't pass my car through inspection without knowing why the "check engine" light was lit.

 
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11-22-04, 11:19 AM   #15  
I just went to Autozone this afternoon with the intent of purchasing the O2 Sensor ($52) and the hope of them showing me WHERE the sensor is located.

The woman who was helping me hooked up the code reader to the car and confirmed what DMV said, Trouble Code P0135 (FOR FREE, not $100 like the dealer). She ALSO said that this COULD be related to the replacement of the FIRST sensor since the light came on within a few days. She said it could also be a fuse, but I didn't see a fuse labeled O2 sensor.

She suggested that she reset the computer (FREE, NOT $100 like the dealer) and wait a few days to see if the light comes back on. Well, I stopped for lunch, and started the car, light came back on.

I may go tomorrow to buy the sensor, but can someone give me advice on replacing it?? Don't want to sound stupid, but not sure WHERE or WHAT to look for. All I know is that it's before the catalytic converter (is that even right?) Also, the readout stated "Sensor 1, Bank 1". Does this indicate left or right side?

Thanks.

Dave

 
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11-30-04, 08:16 AM   #16  
I ordered and picked up the new sensor from Autozone. It is a front sensor, and I called the dealer today and asked him about "sensor 1, bank 1". He stated the "aftermarket" code readers give different results, whereas HIS code reader would tell me whether it's the left or right side sensor. He DID confirm it was the front sensor, and both of them are the same.

If I can't figure out if it's the left or right, I will replace one of them and go to autozone and have the code reset and see what happens.

Is there any way to test the sensor when I remove it to determine if it's defective??

Thanks.

Dave

 
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12-07-04, 11:48 AM   #17  
I think you guys gave up on me!!! '

Anyway, I replaced the O2 sensor last sunday, went to autozone yesterday for a code reset, and it came back on after 2 start cycles. I went back today and the same code came up P0135.

The guy at autozone said the two front sensors are DIFFERENT, the one I purchased and installed was $52, and the other one is $106. The description comes up as "Rear Converter - Sensor located before the catalytic converter".

The sensor I replaced is the one visible from up top, on the left side inbetween the manifold and the radiator fan. So I assume the other sensor is on the other side of the engine (back of the engine compartment, engine is transverse mounted).

The sensor I took out was also a bosch, looked identical to the one I replaced it with. Does that mean its the one the dealer already replaced??

 
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12-07-04, 02:44 PM   #18  
Based on price alone, it probably the same sensor the dealer replaced. I doubt autozone would charge $106 for a sensor the dealer charged $100 for. Wait for another opinion though.

I don't think an O2 sensor can be tested out of the vehicle. You may want to have the other sensor professionally tested before spending $106. Call around for pricing.

 
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12-07-04, 03:01 PM   #19  
Sensor 1 bank 1 should be the pre catalyst sensor on the side of the engine with number 1 cylinder.If you had a scan tool you could disconnect them until you see the 1 you want go dead.You could disconnect a sensor and drive it until it sets another code and see if it is the right sensor and continue through a process of elimination.

 
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12-08-04, 10:24 AM   #20  
Jeff67 - I think you may be correct regarding the sensor the dealer replaced, being they charged $100 for a $52 sensor. When they quoted me $400 to replace the second sensor, it was prob. $200 for the $104 sensor, less the diagnostic fee of $100. ($200 sensor, 100 labor, 100 reset computer)

Davo - I will verify which is cylinder #1 before buying the sensor. Autozone tried to order it yesterday, but it was out of stock from their supplier, so they couldn't order it. Do you have a particular website where I can order the sensor?

Thanks.

Dave

 
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12-08-04, 12:05 PM   #21  
According to my owners manual, Cylinder 1 is in the rear (I replaced the FRONT). Sounds like I replaced a perfectly good O2 Sensor!! Well, it was good practice & I kept the old one incase the replacement fails. After another $100 for the correct sensor, STILL cheaper than dealer.

Hoping you can refer me to a website to buy the sensor.

Thanks!!

 
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12-08-04, 02:24 PM   #22  
You could try www.rockauto.com
and see what they have.It or the Autozone site are places to start.

 
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