What code P0102 means
MAF sensor signal is below the expected range. Most often a failed sensor, a disconnected plug, or wiring damage between the MAF and the DME. Confirm 5 V reference and ground at the MAF connector before condemning the sensor.
How to read a MAF code
MAF codes mean the DME has lost confidence in the mass air flow sensor’s reading. The reading may be out of range, may be flat (not changing with engine load), or may disagree with the calculated model value.
- Inspect the MAF connector.
A loose or oxidised connector is the most common cause of P0102 (low input). Clean and reseat before condemning the sensor.
- Inspect the MAF element.
A dirty hot-wire or hot-film element reads low. Cleaning spray is worthwhile first; replace the sensor if cleaning doesn’t restore the reading.
- Verify 5 V reference and ground at the MAF plug.
With ignition on, back-probe the MAF connector. A missing 5 V reference is a wiring fault, not a sensor fault.
- Read MAF live vs. calculated model.
Beemuu shows the MAF reading next to the DME’s calculated model. A reading that’s consistently 15%+ off the model value points at the sensor or a vacuum leak ahead of it.
Related codes in the same family
A DTC tells you what a control module decided is outside its expected range. It does not automatically identify a failed component. Read freeze frames, compare related codes, and inspect live data before changing parts. Service functions and coding operations are write paths — use a battery maintainer where the procedure requires stable voltage and never perform writes you do not understand.
P0102 questions
What does code P0102 mean?
Mass air flow circuit low input.
Is P0102 a BMW-specific code?
No — {code} is a generic SAE J2012 code; it applies to every OBD-II vehicle, not just BMW.
How do I read P0102 with Beemuu?
Connect on K+DCAN or ENET/DoIP, run a vehicle scan, and look up P0102 in the fault list. Beemuu preserves the code, description and freeze frame before you clear anything.
What does the severity mean?
Critical means the code is usually associated with drivability or safety; warn means investigate soon; info means it is a state or condition rather than an outright fault.