After I got SES light, I disconnected the battery (both cables), and that resetted the light. But now I seem to get poor fuel economy (72 miles for a quarter of the tank). Do I need to reprogram ECU, or the cause is just the way I drive? (No speeding, freeway driving)
Check the ECU learn sequence from the FSM; ECU needs certain drivin conditions sequence to optimize after things like new MAF, reset etc. Thats the 'reprogram', will eventually do that itself.
'By tank' -measurement is VERY shaky. Lots variables from vehicle tire pressure to connection/ voltage fluctuations to gas station mafia pump metering may give 20% mpg differences...
Lots reasons for mpg variation beyond overcomputerization: Draggin handbrake cable may cut 10% from mpg, A/T gearlock doesnt engage...
No you don't need to reprogram your ECU. You need to fix the problem that triggered the SES to begin with. Resetting the ECU to turn off the light is not the solution. The light being triggered indicates that the ECU detected a fault that needs to be investigated.
Nirav
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