Check Engine Light With Code P0170 on Toyota Tacoma

Problem Description and Possible Solution

Occasionally, the mass air flow sensor can go lean and set a code P0170 for fuel system lean. This in not an oxygen sensor problem. If there are no vacuum leaks, the mass air flow sensor may need to be replaced. Our technicians remind us to use a factory part because the aftermarket rebuilds are very inconsistent.

Problem Data
RepairPal Verified
Average mileage: 173,000 (110,000–235,000)
4 model years affected: 1995, 1996, 1997, 1999
9 people reported this problem
Viewing 1 - 4 of 4 comments
Don't buy a new Mass Air a Flow Sensor. Clean the old one. I've cleaned the old one 2 or 3 times now -- still have factory original. Can easily be accessed and cleaned with a Q-tip and rubbing alcohol.
This is a common problem that is always misdiagnosed due to codes telling mechanics that it is a bad O2 sensor. The problem is a bad TPS Throttle Position Sensor that has sections that do not send the correct signals to the computer .An ohm meter test with a Fluke ohm meter will show the flat spots in the sensor . Replacing TPS will solve stumble & check engine light on due to a too lean condition .
Mine did this. Cleaned it with a can of spray injector cleaner. Warning. Spray softly, mass air flow sensor has very fine wire elements in it that can be damaged.