# 2001 3.5 LE "P0158,P0159" and Poor gasmileage HELP



## kdriscoll (Nov 28, 2010)

Hey there I’m hoping someone can help me will some codes and gas mileage issues. 

I have a 2001 Pathfinder 3.5 LE A/T 4x4 151,000miles. . I haven’t really driven the pathfinder very much in the past year. I noticed I was getting horrible gas mileage and the check engine light came on. I tested the code and it gave a “P0158, P0159” . So I changed the air filter (it was very very dirty) and I replaced all 6 spark plugs (champion Brand) and replaced fuel filter and reset the code. (3 weeks ago I did all this)
Drove the car for about 3 tanks of gas and noticed I was getting 10mpg or 13.5mpg all highway. “P0158, P0159” code came back on friday while I was out of town. Driving home today I also got a “P1320 and P0303” 

So I have a couple of questions. Can the O2 sensors “P0158, 0159” cause gas mileage to go down that low? 
I have been trying to research all of this and I have read about MAF sensor. Could this be faulty or dirty cause “low gas” and “p0158, p0159” codes to come on ? 
As far as p1320 and p0303 I’m hoping I don’t have to replace an ignition coil. 

Please help any thoughts on what I should do? Clean O2, MAF sensors or replace? Gas issues? Any help would be great to point me in the right direction.


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## jdg (Aug 27, 2009)

http://en.allexperts.com/q/Nissan-Repair-825/2009/1/99-Pathfinder-O2-Sesion.htm


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## kdriscoll (Nov 28, 2010)

Thanks for the quick reply. I read the bulletin. Can you tell me what the exact sensor or sensors and location I should replace with the "p0158, p0159"error code.


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## daytoncj (Nov 29, 2010)

I'm also looking for a clear explanation on these error messages. I did also read the bulletin and have found some other info as well, but I haven't seen a write-up or how to for replacing the sensors. What is the cost of the reflash of the ecm to the 2002 software version? Does the dealer do this at no cost? What do they typically charge for the sensor replacement?

Thanks for any info, I'm a new member and appreciate this knowledge base.


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## kdriscoll (Nov 28, 2010)

DAYTONCJ- Are you seeing a drop in performance or gas mileage since you started to get the Error codes? What kind of mileage are you getting?


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## daytoncj (Nov 29, 2010)

@Kdriscoll - hard to say. I bought the vehicle three days ago and have gone through 1 tank of gas. I pulled the codes and went straight to this forum. I've driven mostly highway so far and haven't noticed any shocking gas mileage. However, the person I bought the car from mentioned this was a common problem and that the 02 reflash/sensor change seemed to fix the issue. This was confirmed by a few posts on this forum and other forums - but no real detail was given.


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## smj999smj (Jan 1, 2006)

Nissan TSB# NTB02-006 refers to the rear oxygen codes you have. It says it may be due to cracked O2 sensor elements and says that the incident sensors should be replaced. Also, the ECM "may" need to be reprogrammed with an updated program (not a 2002 program). To determine this, one would need to use a Nissan CONSULT scantool to find out the current ECM program part number of the vehicle and compare it to those listed on the TSB. If it has the updated program already, then it does not need to be reprogrammed. If it has the outdated software, then it does. ECM's and their reprogramming is covered up to 8 years/80000 miles per the long term emmissions warranty. What it will cost to reprogram if it is not covered will vary on the dealer. An hour's labor is typical. The part number of the ECM depends on the pro date of the vehicle (break date is 8/1/00) and whether the trans is AT or MT. The part number of the sensor is also dependant on the same break date. Your codes indicate the left (or, driver's) side rear (aka "downstream") O2 sensor. Up to 8/1/00 would be 226A1-4W001 and 8/2/00 and later would require 226A1-4W010. Rear O2 sensors are strictly monitoring sensors and have absolutely no affect on gas mileage and these codes are not set by a dirty MAF.

The P1320 & P0303 codes almost always indicate a failed ignition coil on #3 cylinder and can cause poor mileage.

Champion spark plugs have no business in a Nissan and can also cause poor fuel mileage and other drivability concerns. The best plug to use is the original equipment plug, an NGK Laser Platinum #PLFR5A-11 (or, stock #6240) gapped at 0.044".

If you want to clean the MAF, then do so, but do it with care as to not damage the delicate hotwire. FYI, these and other Pathfinder models were never known for their good gas mileage. 16-18 MPG is pretty typical. Aggressive driving will yield less. Conservative driving may get you up to 20, but don't expect more than that. Also, Nissan air filters are much better at keeping dust out of the engine and MAF sensor than most aftermarket filters.


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## jdg (Aug 27, 2009)

smj999smj said:


> Champion spark plugs have no business in a Nissan and can also cause poor fuel mileage and other drivability concerns.


x1000...
I won't even run Champion plugs in my lawn mowers...when the book says to actually run Champion plugs!
NGK...all the way...


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