Fix code P0133 P0139 P0170 P0173 P0171 P0174 P1136 P1138 P1141 P1143
If you own any of the above vehicles with the 1.8T, 2.0, 2.8/3.2 VR-6, 2.8 V6 90° and 4.2 V8 engines and have any of the listed lean codes, head right for the Mass Airflow Sensor (MAF).
These lean codes can be set by a MAF that has a contaminated or damaged hot film element. When that happens, the MAF sensor doesn’t send the correct air density/volume information to the PCM and it cannot calculate the proper amount of fuel. The O2 sensor then generates a low voltage, indicating a lean condition.
Start by checking for vacuum leaks under the hood. Typical vacuum leaks occur at the fuel pressure regulator, the PCV valve, canister purge valve, and brake booster hoses. purge valves, and brake booster hoses/lines. Next, check fuel pressure. If you have a scan tool, select live data and check for MAF data. At idle with no load you should see these “grams per second” readings.
1.8 Turbo 3-5 GPS
2.0 3-4 GPS
2.8 VR-6 4-5 GPS
2.8 90°V-6 4-5 GPS
4.2 V8 5-7 GPS
If the sensor isn’t reporting these values, replace the MAF.
© 2012 Rick Muscoplat
Posted on by Rick Muscoplat