P0021 2002 Nissan Maxima Sedan -

Question

Hi I am having 2002 Maxima SE 71k miles . Recently got it serviced (Oil and brake pad-rotor changed from Nissan service center. After a week, it started showing SES light. On checking it gave me P0021 code.
My mpg has gone down and now it is not showing the SES light also. I din't do anything other than just opening the hood to see if any leakage or something.
Plz guide me how to get it fixed.

Answer 1

There is a valve in the engine that advances and retards the engine timing (this is done to improve gas mileage and engine performance). The valve (Intake Timing Control Valve) is controlled with engine oil (Hydraulic valve). If the engine oil is dirty or is not the correct weight, then the valve can get stuck which could cause poor gas mileage.

If the light is no ON right now, it possible that the valve is no longer stuck and MPG should improve. If the light comes ON, ask the shop that change the engine oil if the correct oil weight was used. Should have 5W-30 or 10W-30.