MAF sensor for P0171 code

[noahedvalson]

Greetings fellow Corolla owners. I have a 2000 LE w/ about 73K on it. Last week I got the P0171 code, so after reading several forums, I cleaned the MAF sensor, replaced oil and air filter, then reset the code. The light came back on with same code within ten miles. I read a thread where one owner cleaned the sensor and even checked it w/ a meter, but everything checked out OK. He replaced the sensor anyway, and it fixed the problem. I am thinking that replacing the sensor is my best bet at this point, so I am wondering if it matters what kind I get. Dealership wants 160 bucks, while I can get a refurbed Cardone brand from Schucks or Autozone for 80. Does anyone know of possible complications with getting the aftermarket one?

[jcturbo]

what did you clean the MAF with?? Did you hose it down really good?????

I clean my MAF everyother oil change. I got in the habit when I was a mechanic to clean them on other people's car when they came in for oil. they always noticed a big difference but had no clue why.

If you cleaned good and didn't have a noticible improvement in Engine response, then you might have more than one problem. have you tried spraying Carb Cleaner around the intake while it's running to see if you have a vacuum leak?

[toyomoho]

Might get a repair manual, the map sensor can be troubleshooted. Could be something else, the engine is running too lean. Plugged injector, low fuel pressure, vacuum leak, O2 sensor, MAP or coolant sensor.

[noahedvalson]

I am crossing my fingers that this is just a MAF sensor problem, cuz I would have to take most of the other problems to a mechanic... I have read sooo many posts about the MAF sensor going out in these models, so I am going with prevelance. here.

[noahedvalson]

I just wanted to give any future searchers an update on the thread. After cleaning the MAF sensor (twice), and then replacing it, the CEL still came back on. I finally got a hold of a friend that is a mechanic and had him take a look at it. The culprit was a leaky O-ring on my injector valve. It had several cracks in it. One thing that may help diagnose in the future, is that I didn't have the same symptoms of the other posters as far as idle and engine hesitation. Also, the CEL would always come on (all 3 times) when I was at IDLE. The mechanic told me that the leaking was occuring at idle (I'm not sure why/how), so that makes sense. Hope this helps somebody, cuz a new O-ring only costs a few bucks!

[bonnie*]

DTC code P0171 : P0171 System Too Lean (Bank #1) always does not relate to MAF Sensor.
This code is generated and recorded when air-to fuel ratio feedback is stable for more than two scan cycle.

You have to check following things:
1) Blockage in Fuel Injection system & EFI relay.
2) MAF Sensor.
3) Low fuel pressure or Gas leakage in exhaust system.
4) Open or Short in Main Heated Pre-Catalyst Oxygen Sensor (Bank 1, Sensor 1)
5) PCV Valve and hose.

If you do nor know how to check, please ask, someone will help you out here.
I suspect 1), 4) and 5).


Or if you identify the cause by now, Please provide you complete feedback that how you solved it.

Thanx
bonnie*

[bonnie*]

JUST DO NOT SIMPLY THROW NEW PARTS IN SYSTEM, ONE BY ONE.
CHECK AND MAKE SURE IT'S FAULTY BEFORE YOU REPLACE.

JUST FOR MORE INFO, READ THRED:
http://www.toyotanation.com/forum/t171748.html