P0102: Mass or Volume Air Flow "A" Circuit Low
The MAF sensor signal voltage is lower than it should be, so the computer thinks almost no air is coming in.
What P0102 means
The MAF sensor sends a voltage or frequency signal that rises as more air flows into the engine. P0102 sets when that signal stays below the lowest value the computer considers possible for a running engine. RepairPal lists an unplugged sensor, damaged wiring and loose or corroded terminals as typical triggers, along with a failed sensor. A large air leak after the sensor can also make the reading low, because some of the air never passes over the sensing element. In many cases drivers notice nothing at all except the light and slightly worse gas mileage. Shops confirm the low signal on a scan tool, then back probe the connector for power, ground and signal voltage while gently moving the harness to catch an intermittent break. If the wiring is good and the sensor is clean, the sensor is replaced. RepairPal warns that sensors often get replaced when the actual fault was a connector or a vacuum leak, so test first.
Common symptoms
- Check engine light on
- Often no other symptoms
- Poor gas mileage
- Hesitation or stalling in some cases
- Rough idle
Most common causes
- MAF sensor unplugged or connector loose
- Broken or shorted signal wire
- Corroded connector terminals
- Failed MAF sensor
- Very dirty sensor element
- Large air leak between the sensor and throttle body
What to check yourself first
Unplug the MAF connector, check for bent or green pins and plug it back in firmly. Check the fuse that feeds the sensor. Inspect the intake ducting for a disconnected or split hose.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Electrical diagnosis to find a wiring or connector fault | $122-$179 | A broken wire or bad pin is a common cause of a low reading. |
| Clean the MAF sensor yourself | $15-$20 | About $17 for a can of cleaner if the element is coated. |
| Replace mass airflow (MAF) sensor | $274-$381 | When the sensor fails a test with confirmed good power, ground and signal wiring. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
Related repair guides
- Jeep Grand Cherokee Stalling or Won't Start? TIPM Fuel Pump Relay and Alternator Recalls (2011-2014)
- Hyundai Tucson ABS Module Fire Recall: Which Years Should Park Outside, and What the Free Fix Is
Related codes
- P0100 Mass or Volume Air Flow "A" Circuit
- P0101 Mass or Volume Air Flow "A" Circuit Range/Performance
- P0103 Mass or Volume Air Flow "A" Circuit High
- P0171 System Too Lean (Bank 1)
- P0112 Intake Air Temperature Sensor 1 Circuit Low