# Nissan Xtrail QR25 bad fuel consumption



## salimsaid (Jun 5, 2017)

Hi all, my nissan xtrail is running at 5KM/L which is not normal,

i used an obd 2 scanner to read the engine codes, the check engine light is oN.

I got two error codes

1. P0420 - Powertrain Catalyst System efficiency below threshold (Bank1)
2. P0138 - Powertrain 02 Sensor Circuit High voltage (Bank1 Sensor 2 )

Sorry i can't upload a screenshot for the read codes, my account is still new.

Do i need to replace both the catalytic converter and the 02 sensor ?

Where is Bank1 sensor 2 located ? 

I am thinking of replacing all 02 sensors since the car has already run 130K Miles, is there a possibility of improved fuel efficiency after replacing the 02 sensor ? Thanks.


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## quadraria10 (Jul 6, 2010)

Salim read through the forum a bit or do a search. There is lots of info about 02 sensors and catalytic converters

FYI-- this is a good read

The Misleading Nature of the PO42O Code - Eastern Manufacturing


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## greenbay (Jun 14, 2018)

Hello Salim could you solve your problem ? My fuel economy is too low after the recent engine tune up. I have a T30 2.5 (QR25DE AUTO) and currently its doing about 5.5 kmpl. It was doing about 7kmpl. I don't see the check engine light turns on. I asked the mechanic to recheck and he said its fine. I didn't change the roads or the driving pattern. What can be the issue? Usually what is the best fuel economy of a qr25de auto ?


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## greenbay (Jun 14, 2018)

After the 2nd engine tune up. Now My car is doing about 6.5 to 7 kmpl. Actually what the best fuel consumption of a x-trail qr25de auto ?


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## quadraria10 (Jul 6, 2010)

Best is around 11 to 12 km per liter, but that would be pure highway on fairly flat terrain with summer gas. Worst is about 6 to 6.5 km per liter which involves pure city driving in winter conditions and winter gas formulations.
I am curious what was involved in your tune-ups? Other than changing oil and filter, maybe air filter and sparkplugs there is not much to be done. It is good to change oxygen sensors when they are approaching the end of their service life which is somewhere between 80,000 and 150,000 kms. As they degrade they provide less accurate info to your cars computer and you will burn more gas as a result. By the time the check engine light goes on, it means the O2 sensor is operating below 75% efficiency.


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