# Bad Fuel Mileage



## Leprechaun (May 6, 2021)

Can anyone help I have a 2012 Versa 5 door Use to get great gas mileage could go 2 /2.5 weeks on a tank of gas .
Mileage started going bad a tank a week , had it tuned up wire /spark plugs still bad gas mileage.

Tks
L


----------



## rogoman (Dec 16, 2004)

Without going into great detail, here are some causes of bad MPG:
1. Leaking/dirty fuel injectors.
2. Dirty spark plugs.
3. Dirty air filter.
4. Marginal O2 sensor.
5. Dirty MAF.

You might also consider doing an ECU code readout with a portable scan tool to see if any fault codes are set. The tool can be purchased at most auto parts stores or online at Amazon.com. Also most auto parts stores will perform a code readout free of charge. Post the actual codes here on the forum so that we may be able to help you further. If there is one or more fault codes set, they can help point to the malfunction.


----------



## VStar650CL (Nov 12, 2020)

rogoman said:


> Without going into great detail, here are some causes of bad MPG:
> 1. Leaking/dirty fuel injectors.
> 2. Dirty spark plugs.
> 3. Dirty air filter.
> ...


6. Dead or malfunctioning IAT sensor (Intake Air Temperature)
7. MAF calibration (perform IAVL)


----------

