How to fix a MAF Sensor CEL Tutorial

Almost all cars after the 90's have a MAF sensor. The MAF sensor detects airflow thereby sending signals to the engine to adjust how much fuel to deliver. They oftentimes get dirty from years of driving, and the sensor gets clogged with dirt and oil causing poor gas mileage as well as poor performance. Your car may even throw a Check Engine Light (CEL). In my opinion, most MAF sensors don't need to be replaced, but just a good cleaning will make the MAF sensor perform like new again.

Disclaimer: This is for demonstration purposes only. Removing and mishandling the MAF Sensor can be a costly mistake. Some of these newer sensors go for a few $100. Proceed at your own risk.

Materials:
CRC/Mass air flow sensor cleaner
Flashlight
Q-Tip

Tutorial:

1. With the car off and key removed, disconnect and remove your MAF Sensor

2. Looking down the MAF sensor with your flashlight, you should see two platinum wires with two tiny sensors in the middle of them. If these are covered in black gunk, take your CRC MAF cleaner and spray it at the wires. The cleaner should evaporate quickly. You can stop here if the wires become clean.

3. If the gunk is still stuck on the wires, grab your Q-tip and spray some MAF cleaner on it and again down the hole. Carefully clean and rub the wires as they are very fragile. If you break the wire, then you'll need a new sensor.

4. Reinstall your MAF sensor. Turn on your car and go for a test drive. If there was a CEL, it should now be gone. Enjoy better gas mileage and car performance!

Toyota 4runner CEL P0171 and P0120 Fixed

Image from yotatech.com

Disclaimer: This is for demonstration purposes only. Removing and mishandling the MAF Sensor can be a costly mistake. Some of these newer sensors go for a few $100. Proceed at your own risk.

Click here for an Update Oct. 7, 2011

P0171 - Fuel system running lean
P0420 - TPS sensor

Completely clean the MAF sensor *FIXED*!

CEL light went on in our '00 Toyota 4runner a couple days ago. 100K miles and going strong. Using Toyota Techstream Software with a Tactrix cable, 2 codes were read. So I figured if I replace the TPS sensor, clean the MAF, replace spark plugs, and then reset the ECU by unplugging the battery, then all would be fixed. Not exactly.

Even after replacing the TPS sensor and spark plugs, the codes kept popping up. Turns out I only cleaned HALF of the MAF sensor. I only cleaned the orange bulb and wires. What I forgot to clean was the internal wires of the MAF sensor. 

When looking down the long shaft of the MAF sensor, you'll see 2 thin looking wires at the end of the shaft. After cleaning the two hidden MAF sensor wires with CRC/11 oz. Electronic Cleaner and a Q-tip, a chunk of soot was left on the Q-tip.

I switched back the old TPS sensor, and reset the ECU again, and BAM, all was well. The car drove like it was brand new again. I'm very confident that our 4runner will be getting kick butt gas mileage once again.

PS: On another note, I made an error while troubleshooting causing the car's idle to run screwy. I left the radiator cap slightly loose causing the IAC to malfunction resulting in a rough idle. *Face Palm* Once the radiator cap was tightened completely, the car was back to 100%. Thought I'd throw this out there in case others run into the same problem.