# Diagnosing a p0420 code for 2005 nissan x-trail 2.5L



## salimsaid (Jun 5, 2017)

I own a 2005 nissan xtrail with a 2.5L engine (QR25DE). I have problems with my vehicle,

too much fuel consumption ( 3.8km/L ) My car has a 60Liter tank , my last fuel up gave me 229KM until the car fuel tank well completely dry; i had to refuel from a jerrycan as the engine went off somewhere far from the petrol station.

I have loss of power, the car can't go more than 120km/h; and when i get to 80km/L to car struggles to get to a higher speed.

I have problems with my catalyst as i hear rattling sounds coming out of the catalyst. I have the error code >> p0420 catalyst system efficiency below threshold

Please see below screenshots from torque pro app.

1. Air fuel ratio screenshot 
https://postimg.cc/image/lpc3yi67f/

2. Rich/lean test screenshot
https://postimg.cc/image/c4shbltq3

3. Vacuum reading screenshot 
https://postimg.cc/image/chjvhtekr/

02 sensor Bank 1 Sensor 1 Graph screenshot 
https://postimg.cc/image/kaaj9ra97/

02 sensor Bank 1 Sensor 1 wide band voltage screenshot 
https://postimg.cc/image/v9vqle397/

What should i look for to fix the problem ?


----------



## quadraria10 (Jul 6, 2010)

The Misleading Nature of the PO42O Code - Eastern Manufacturing

Have a read of the above. Your engine obviously has some issues. You may want to go through the forum and read about similar issues. Good luck.


----------



## MikeHJ (Mar 7, 2017)

So you have poor fuel mileage, a rattling sound from the cat converter, poor power and a 420 engine code.

Those are all the typical symptoms of a bad catalytic converter, you should replace it


----------



## salimsaid (Jun 5, 2017)

@MikeHJ Can a bad cat alone cause poor mpg ?


----------



## cartman_to (Nov 29, 2017)

When my cat went bad (0420 code) my gas mileage wasn't bad. Other than the CEL there were no other indicators. How long as the CEL been on?

Have you changed your spark plugs and air filter recently? If you haven't changed your air filter in 25,000km or less km you drive in very dusty/dirty roads then I would change it. Spark plugs should be changed every 100,000km to 120,000km.


----------



## MikeHJ (Mar 7, 2017)

salimsaid said:


> @MikeHJ Can a bad cat alone cause poor mpg ?


Yes. particularly if the core dislodges and partially clogs the exhaust flow.


----------



## quadraria10 (Jul 6, 2010)

I have been lucky and avoided any cat related problems so far. But for anyone who wants to change theirs or needs to, it should be pointed out that the one used on the 2.5 X trail is the same part as was used in Altimas and Sentras with the 2.5 engine. If you are in Canada this is important to know as many places seem to think its X trail specific or a dealer only part.
For the original poster, you haven't mentioned what mileage you are at, nor when you acquired the X trail. If you just bought it you may want to have the engine examined more closely. It may have overheated or suffered cylinder issues. I would be curious to know at what mileage were the 02 sensors replaced, if ever?


----------



## X-hale (Apr 17, 2017)

All your symptoms point towards a bad catalytic converter. I had the same code and I knew that PO420 seldom indicated a bad cat. I replaced the O2 sensors and did a few other things. I finally broke down and bought an aftermarket cat...problem solved.


----------



## quadraria10 (Jul 6, 2010)

Hi X-Hale,
I think you are probably right about his catalytic converter needing replacement. I am just wondering why it went bad? Do you know what happened with yours?


----------



## MikeHJ (Mar 7, 2017)

I know we all hope that the P0420 code is caused by something cheaper to fix than a bad cat. And yes, in certain circumstances, various things can trip a P0420 code.

But, at the end of the day, all of the OP's symptoms point to a bad cat and the code tripped is the code for a bad cat. I'm not sure why he has posted twice asking the same question.

You can pick up an aftermarket direct fit for $120 CDN on ebay.

https://www.ebay.com/itm/FITS-NISSA...aMBe6&fits=Year:2006|Make:Nissan|Model:Altima


----------



## X-hale (Apr 17, 2017)

quadraria10 said:


> Hi X-Hale,
> I think you are probably right about his catalytic converter needing replacement. I am just wondering why it went bad? Do you know what happened with yours?


The car had 200,000 km on it when I bought it. The original owner had changed one O2 sensor so I assume he was having some sort of issue. It may have damaged the cat which failed a couple of months after I bought the car. I changed both O2 sensors and the cat. I immediately felt more power and got better mileage.

P.S. I just realized a couple of weeks ago that my front fenders are plastic. I never knew noticed for over 14 months.


----------



## quadraria10 (Jul 6, 2010)

Thanks for the answer. I changed mine around the 150,000 km mark as preventative maintenance and also noticed an improvement in engine performance. Now at 203,000 and have never had the P0240 code. The complete exhaust is still the original, albeit with some new hangers welded on, and a pipe over for a section where two flanges meet and rusted out.
You have to like those front fenders, no rusting there, and I once got sideswipped by an OC Transpo accordion bus. Came close to being serious, but instead the back end of the bus just caught my drivers side mirror, and spun it around, then drivers side front fender. Fender had a slight scratch but popped out perfectly, and the mirror I was able to turn back into proper position and it got a scrape of the outside of the plastic cover. I learned that even when you are stopped at a light, and the bus beside you is turning left and manages to hit you from the side with its rear, no fault insurance applies and OC Transpo tells you to call your insurance company. Fortunately, the only real damage was two small scratches which I have kept as battle scars.


----------



## MikeHJ (Mar 7, 2017)

quadraria10 said:


> I think you are probably right about his catalytic converter needing replacement. I am just wondering why it went bad?


While you are correct in thinking that a cat doesn't really "wear out" in that there aren't any moving parts or consumable things inside, it is intended to run at some pretty serious temperature and the thin metal casing can warp, etc. One good whack from a rock or a chunk of ice on the road could easily knock the mesh loose inside without leaving a big dent of the outside


----------



## quadraria10 (Jul 6, 2010)

Thanks for answering MikeHJ. I guess road damage is possible, but you have to be pretty unlucky. One of the best comments I have read about them is
"A converters life-span is determined by what happens upstream in the engine. Even when they fail, they seldom plug up and cause back pressure…They just stop converting…"
https://community.cartalk.com/t/catalytic-converter-life-expectancy/43896


----------



## MikeHJ (Mar 7, 2017)

quadraria10;1699451Even when they fail said:


> https://community.cartalk.com/t/catalytic-converter-life-expectancy/43896[/url]


I find that a funny comment. Every cat converter I have ever changed (because the cat was actually bad), chunks of the grid fell out in my hands when removing the old one.Admittedly not a statistically large sample, but "they seldom plug up" is certainly not my experience.

It may be a more canadian thing because of the temperature extremes and the road salt.


----------



## quadraria10 (Jul 6, 2010)

Admittedly its a bit simplistic, but I do like the notion that maintaining your engine will help maximize cat life. I have never had to replace one, but I have also never kept a vehicle past 200,000 kms either. In that weird spot where I want to maintain it, but I also don't want to spend unnecessary money if there is no need.


----------



## MikeHJ (Mar 7, 2017)

quadraria10 said:


> Admittedly its a bit simplistic, but I do like the notion that maintaining your engine will help maximize cat life. I have never had to replace one, but I have also never kept a vehicle past 200,000 kms either.


Absolutely! I tend to buy cars that have between 150-200K on them so I have probably seen more cat failures than you. I research the service records and inspect the hell of them, but there is always the risk of an unexpected expensive repair. I have a "walk away" repair price point of about 50% of the purchase price.


----------



## quadraria10 (Jul 6, 2010)

I hear you about hugely expensive repairs, but when you have kept the car for over 9 years, paid 20K for it with 50,000 kms off a 3 year lease, and its in great shape, its hard to get your head around the idea that it is now worth maybe 3K. Moreover, if I did not know how to save on maintaining and repairing it, I could have easily spent multiples of what I actually did in looking after it.
In another thread about daytime running lights, the original poster mused about his most recent service coming with a 2K list of repairs and mused that maybe next year he would have to get rid of it. I realize that my recent repairs if done at a dealership would have probably pushed me to that as well.

Daytime light module replacement-- Dealer price including taxes approx $500
Rear Caliper replacement-- dealer w taxes 420
Front Control arm replacement-- dealer w taxes 450
Front outside tie rod replacement-- dealer w taxes 200
Front driveshaft inner boot replacement--dealer w taxes 350 +
Rear wheel bearing and hub replacement-- dealer 201 for bearing, 28 for retaining clip, 350 + for hub and almost 200 for labor.

Happy to report that my actual expenditures for the above came to approx 600 everything included. Prior to that this year, only repair was to the oil cooler which cost me 170 to fix. Sure beats the dealer cost of about 700 to replace that. So in first 8 months of its 12 year the X has cost me approx 1100, which includes the price of my new custom seat covers. Car drives great and is in excellent shape.


----------



## MikeHJ (Mar 7, 2017)

That's kinda what gets me going about some of the replies on this forum. If you're going to diagnose an issue by swapping out parts that "could" be causing the issue, then you're probably going to spend a lot more money than just starting with the obvious.

The P0420 code "could" be caused by something unrelated to the gas mileage issue, but you can spend a lot of time and money swapping airfilters, O2 sensors, spark plugs, etc. in order to save $130 on an aftermarket cat converter. PLugs are $10 each, cheap air filters are $15, o2 sensors are $40-$60 each, so it is not hard to spend an extra $150 and not solve the problem.


----------



## cartman_to (Nov 29, 2017)

Hi quadraria10, 

Wow, you have a great mechanic! I paid $550 just for my two control arm replacements. This was back in 2016 though.

I've had a bad year in repairs for my 2006 x-trail too.

- Left and right hood hinges (~150 each side)
- Front stabilizer bar links (~150 both sides)
- Rear left and right wheel bearings (~$400 both sides)

I also had to change my front brake pads + rotors and my rear brake pads (~$500). I amhaving to change my brakes every 2-3 years on my X-trail now. I drive about 12,000km per year. I don't drive aggressively but it's mostly city (suburban) driving (not your downtown bumper to bumper type of traffic). My mechanic says most likely the calipers stick slightly causing pads to wear more. However he doesnt see any major seizures (e.g. overheating or very uneven brake wear) so he said not to replace the calipers. How often do you guys replace your pads/rotors?





quadraria10 said:


> I hear you about hugely expensive repairs, but when you have kept the car for over 9 years, paid 20K for it with 50,000 kms off a 3 year lease, and its in great shape, its hard to get your head around the idea that it is now worth maybe 3K. Moreover, if I did not know how to save on maintaining and repairing it, I could have easily spent multiples of what I actually did in looking after it.
> In another thread about daytime running lights, the original poster mused about his most recent service coming with a 2K list of repairs and mused that maybe next year he would have to get rid of it. I realize that my recent repairs if done at a dealership would have probably pushed me to that as well.
> 
> Daytime light module replacement-- Dealer price including taxes approx $500
> ...


----------



## quadraria10 (Jul 6, 2010)

Well I source the parts usually, and do most of the maintenance work myself. For the brakes 2 or 3 years with cheaper rotors is about normal, especially in a winter climate where salt is used on the roads. Changing all the calipers and brake lines would probably be great but pricey unless you are doing it yourself, and even if you are, still fairly expensive. Anyway, you will find lots of info here on different repairs and usually how to save a fair bit of money doing it.


----------



## MikeHJ (Mar 7, 2017)

cartman_to said:


> Hi quadraria10,
> 
> Wow, you have a great mechanic! I paid $550 just for my two control arm replacements. This was back in 2016 though.
> 
> ...


LIke Quad, I do most of my own work except for stuff that I don't want to do on jackstands in my driveway.

My mechanic charges $100/hr (which is cheap) and will install parts that I bring him for the labour cost only.

So your cost for the stabilizer links, wheel bearing and control arm work is actually quite reasonable if it includes parts and labour. I'd figure 1.5 hours labour per side for the control arm, 2.5 hours for both wheel bearings and the shop minimum of 1 hour for the stabilizer links and hood hinges.

I would do all of that myself except the bearings (cuz I hate wrestling with the axle nuts) and I'd scavenge the hood hinges from a junkyard. I'd take a chance on cheap control arms and stabilizer links because the car is 12 years old now. So my cost would probably be under $500 for all of the above.

And like Quad, I get 2-3 years out a set of brake pads (50-75K)


----------



## quadraria10 (Jul 6, 2010)

Changing the two control arms takes about an hour and a half, and can be done in half that time assuming no big problems with seized bolts. I waited at the CV shop while they replaced my inner boot. To remove the driveshaft from the car, they always remove the control arm. Anyhow that mechanic for $145 +tax, supplied the OE style inner cv boot, grease and clamps, repaired the driveshaft, reinstalled it, replaced the control arm, and outer front tie rod. ( also involved removing and reinstalling hubnut, and a front link). I supplied the inexpensive arm from autoshack and a Moog pro series tie rod from RockAuto. Basically took the guy and hour and a half, and charged me the same amount to do the whole job as the Nissan Parts dept charges for the inner cv boot replacement kit. Even better, the guy was careful replacing the tie rod, so I have not needed an alignment. After a month car tracks straight and no tire feathering. Glad I found that place. For anyone in the Ottawa area, A1CVTech quoted 125 for the inner cv joint boot replacement (including the boot etc). I paid 145 because I offered an extra $20 for them to change the outer tie rod at the same time. Actually I was so pleased I went round back and gave the mechanic a 10 dollar bill to buy himself a beer.


----------



## cartman_to (Nov 29, 2017)

Thanks guys.

Yes the prices are including parts and labour. I am very happy with my mechanic. He is very honest and never upsells anything. He changes things only as needed. When I changed my crankshaft sensor last year, I asked him about the camshaft sensor. He said if it's not defective why spend the money? I ended up changing it myself anyway as I learned from quad that it's very easy to do. 

I only drive about 30-35k over 3 years so I don't do the mileage you guys do but change my brakes/pads at the same frequency.

I hope to drive my 2006 X-trail for another 3 years and then replace it for a new pre-owned small SUV. At that time it will have ~240k km and my all-seasons, winter tires and brakes will be due.




MikeHJ said:


> LIke Quad, I do most of my own work except for stuff that I don't want to do on jackstands in my driveway.
> 
> My mechanic charges $100/hr (which is cheap) and will install parts that I bring him for the labour cost only.
> 
> ...


----------



## quadraria10 (Jul 6, 2010)

It used to be that you could buy a kit for Altimas and Sentras from the Nissan dealer that included both sensors and for which they charged less than half the price they sell them individually. Apparently this is now a discontinued part number in Canada, but can still be found on Ebay or Amazon in the US with some luck. In this neck of the woods you can also find good independent garages which charge 85 to 90 an hour.
As for control arms, AutoShack formerly Prime Choice sells them for the lowest prices I have ever seen. Bought one and its performing fine. Time will tell, but visually the quality appears the same as others I have bought previously. In fact the balljoint boot looks to be better quality than that found on Beck/Arnley, and is identical in terms of the form and indentations on the bottom to one on a Moog Professional outer tie rod end. If you are willing to pay an extra $15 per you can even get a lifetime warranty on them for as long as you own the vehicle. I was too cheap to buy it, but think its a positive that they are willing to stand behind the product. Otherwise its the usual one year warranty you get on a lot of parts, even those bought at the Nissan dealer.


----------

