OBD-II code: P0171 (lean mix) code: causes?
 

I have a 2001 Protege LX (the 1.6L). My check engine light came on a few weeks ago, so I invested in a code reader. It pulled the above referenced code. According to the Mazda factory service manual, this code can be triggered by any of the following:

• Misfire
• HO2S (front) deterioration
• HO2S (front) heater malfunction
• PRC solenoid valve malfunction
• Pressure regulator malfunction
• Fuel pump malfunction
• Fuel filter clogged or restricted
• Fuel leakage on fuel line from fuel delivery pipe and fuel pump
• Fuel return hose clogged
• Leakage from exhaust system
• Purge solenoid valve malfunction
• Purge solenoid hoses improper connection
• Insufficient compression

I've cleared the code and it hasn't come back since, so for now I'm treating this as a random event. I am having no drivability problems.

However, if it comes back again, I'll have to start thinking about what the root cause is. Does anyone have any experience about what is the most likely cause/fix for this? Spark plugs maybe?

Many thanks.

my 2.0 liter ES threw that code, and it was the MAF sensor.

I was afraid of that. I've read that the MAF sensor is dicey on the Protege. Did you live with the code for a while, or did you replace it right away? Am I harming the engine by ignoring it for a while (the code hasn't yet come back).

How much does a MAF sensor cost? Is it something a home mechanic with more time than money can do?

Thanks again.

if your engine really is running lean, you might not want to ignore it. possible to cause engine damage. i tried to live with the code while i tried to figure out what the problem was, and the engine ran worse and worse every day. eventually, i had to take it in to the dealer to diagnose the real problem. you might want to do that, just to make sure what the problem is. remember, just because they tell you what the problem is, does not mean they have to be the one to fix it.

it could also be exhaust leak before the oxygen sensor, fauty fuel injectors, faulty sparkplugs, faulty MAF sensor.

i had a bank 1 too lean because of a cracked exhaust manifold

MAF sensor, o2 sensor, vacuum leaks, coil packs

my money is on MAF or vac leak