Long story short. Car failed emissions inspection due to the CEL being on and two codes, one for knock sensor and the other for MAF circuit. It passed the Catalytic portion and the actual CO whatever portion. It only failed due to the light and codes.

Did they pull the codes BECAUSE the CEL was on or do they automatically pull them when performing an inspection irrespective of the CEL light??

It's my daughters car and I am not located in N.VA. Thus, I was not there for the test. 2000 Nissan Xterra V6 4x4 new to us. Fantastic shape and runs great.

The CEL is now out (batt grnd strap disconnected overnight). Did this clear the codes or are they still in the memory? I won't see the car for a few weeks so I cannot troubleshoot myself. I have an OBD 2 reader.
Modified by oldmako at 12:00 PM 1/22/2010

Have her run 50 miles varying speeds, and if the CEL does not illuminate, immediately take to the emissions testing center.

That's the current plan. Unfortunately, she had to drive it to school which is in another part of the state which does not require smog tests (and therefore does not have) emissions inspection stations. The light has been out since the battery disc. That was 5 days and 200 miles or so ago.

Thanks for the reply.

My guess is that the codes are still present even with the CEL extinguished. I suggested that she swing by Advance and ask them to put an OBD reader on it. Then, if they're clear to get the car reinspected the minute she can find a station. I'll just have to wait till she is successful and/or I get my hands on the car in a few weeks.


Modified by oldmako at 12:01 PM 1/22/2010

The "not ready to test" is there to avoid the " reset and test" scenerio.

Why not repair the vehicle?

Q45tech wrote:The "not ready to test" is there to avoid the " reset and test" scenerio.

Why not repair the vehicle?

Not sure what you mean by "not ready to test". I assume you mean by the technician who performed the initial test. At any rate, the car will be repaired just as soon as I can get my hands on it. It was purchased from an out of state individual. Northern Virginia DMV's will not tag a car without an emmissions test. The goal was to get the 30 day exemption and then fix the car when I can and then get the permanent tags. The CEL was not illuminated when I bought the car.

I cleaned the intake path up to the throttle plate. During this the MAF was disconnected while the engine was running. That explains code number one (I assume) as the CEL was not on prior to the cleaning. The car had an oily K&N filter and the residue had gummed up the intake path. I wanted that crud out. After the cleaning is when the car failed the test. The CEL and/or the codes are the only reason that it failed the test. It passed the CAT portion and tailpipe percentage test. I still don't know if the tech pulled the codes because the CEL was illuminated or it is SOP.

From the research I have done thus far it sounds as though the KS code is common on this engine and many owners view it as a nuisance because even though it illuminates the CEL, the car runs perfectly otherwise. The only other car I have owned with a KS is my Q. From what I understand, the 4.1 won't run if the KS are shot, or will run very poorly. I am only going on what I have read here, and from a service writer at the dealership.

Mine were replaced by the P.O. and I have had no trouble with them.

The CEL is now out. I don't know if the codes are still there or not. Hopefully in the next one or two weeks I can get another look at it.

Thanks for the input.

Study OBDII! Every ecu has data flags that send ready for emission test to emission station computer system. Without these OK's the system fails you to protect against fraud by those reseting ecu just before test.

50+ miles with multiple cranks and cold to warm to cold cycles are required.

The entire drive cycle [required to clear and get ready for test] is explained in FSM in detail.

It has been the same for 15 years now!

Northern Va's emissions are some of the strictest in the nation matching those of Ma, and actually exceeding Ca in several ways.

Here is what the deal with your car is going to be. Since it is >96 and is OBD compliant the way the emissions test is now run by having our computer talk to the cars' computer. If there are any pending (active or stored) diagnostic trouble code you will immediately be booted from the test and a report will be issued stating why the test was aborted. If there are no pending codes or no priority 1 codes (cel on) your car still may not pass emissions, if the SRT (System Rediness Tests) are not complete. These are self-tests the ecm performs under a set of exact criteria to test an emissions components operation characteristics (ie, negative pressure testing the evaporative emissions system or EGR function). Depending on the car in question (in this case a 99Q) you need at least 4 of the SRTs to set and you have to have the EVAP and EGR.

The dtc for the MAF may have been an old code but if the CEL is on I bet you a dollar that your MAF dtc is live though. As the KS dtc is not a priority 1 code that will turn the CEL on. The dtc sets when the ecm realizes the resistance value of the piezoelectric sensor is not what the computer knows to be true. The MAF might be damaged or contaminated from the K&N I would try some good contact cleaner on the Hot wire if I were you. You will also need to make sure the codes are reset before with hitting the highway to perform the system reset.

Q45tech wrote:Study OBDII! 50+ miles with multiple cranks and cold to warm to cold cycles are required.

The entire drive cycle [required to clear and get ready for test] is explained in FSM in detail.

It has been the same for 15 years now!

Practice what you preach, I hope you haven't been giving out this type of misinformation for 15years?

The entire drive cycle is not required to be completed as is illustrated by this case where some of the SRTs have been set despite the pending and live dtcs that goes against what you are saying.

Here is the actual drive cycle from the book. http://picasaweb.google.com/lh...tlink

Here is the EC link. http://www.nicoclub.com/FSM/Q4...c.pdf

You've got to open your mind a bit buddy and continue to learn.

Do you mean the Two Trip Detection Logic on EC-40 in the 1999 FGY33 FSM?

I think the OP was asking about a "2000 Nissan Xterra V6 4x4."

It's part of two trip logic, but the primary focus is emissions compliance and diagnostic logic.

Oops, not a Q.

It appears that I have broken my Adobe and will have to try again later but they are very similar given the close proximity in years.

Thanks for clarifying.

The end result is that the car passed the test. The CEL never came back on after it was reset. From what I am led to believe by guys who own and wrench on Xterra's, a KS anomaly will not trigger the CEL. I suppose that leaves the MAF as the culprit.

Verifying that the CEL is out is a required portion of the test, as is pulling the codes. At least, there is a separate section on the receipt detailing that portion of the test. That, and the info supplied in responses leads me to believe this is SOP.

New tags on the way, happy kid and happier old man. Crisis averted.

Thanks again.