check engine light

check engine light

Yeterday, I was driving and my check engine light came on, so today I went to auto zone and to figure out what code turned on the light. The OBD II reader said it was code P0171 and it said "system too lean Bank 1" Does anyone know what this means, could it be my O2 sensor or my MAF sensor. The car has 45000 mile on it and its a 2001 CE.

This is my car:
http://www.cardomain.com/ride/417552

Thanks for your help,
iward

my car had the same thing but it was map sensor, thought it was the o2 at first so i put a scope on it and it faine tested the maf it was giving wierd signals changed and problem went away so look into those two things.

Like you mentioned before - this code refers to a condition of System Too Lean (Bank 1) - usually refers to the upstream O2 sensor or the O2 sensor closest to the engine. What this means is that the oxygen sensor in bank 1 detected a lean condition or too much oxygen in the exhaust.

Note it doesn't mean that the sensor is faulty (though it could be a bad sensor in some cases). Probably 90% of the time, the O2 sensor is fine - but almost every mechanic will replace it (they have to make money some how). On 2000+ Corollas - the most common cause for this code popping up is from a dirty MAF sensor in the airbox.

Example here: (not quite identical to the Corolla - but will give you an idea of what it looks like and how to clean it yourself).
http://spydermagazine.com/2002/March/maf_clean/maf_clean.htm

From the symptoms that you described - it sounds like a dirty MAF sensor and possibly dirty throttle body. As both will contribute to hesitation, poor idling, and poor performance. Sometimes it will lead to reduced fuel economy.

I would take a look at the MAF and TB first - cleaning them is minimal in cost and will reveal if any other components may be contributing to this condition (sparkplugs, induction system, ignition, etc.)

thanks I reset the computer and cleaned the MAF sensor with some electronic cleaner spray that I got at radio shack I will just have to see if the light comes back on, it seems to be running fine.

Mine does the same shit because of my intake, makes the engine think its running lean, but I have a 9thgen and don't know much bout the other gens in that regard. If its the same thing though it shouldn't cause you any problems.