OBD Code P0101: MAF Sensor Range/Performance — Clean Before Replace

What does code P0101 mean?

Code P0101 (Mass Air Flow Sensor Range/Performance) means the MAF sensor is producing a signal, but it's inconsistent with what other sensors report (throttle position, RPM, manifold pressure). Unlike P0100 (circuit dead), P0101 is typically a contamination issue.

Symptoms

• Check engine light
• Power loss mainly mid-range (2000-4000 RPM)
• Rough idle, oscillating RPM
• Fuel economy down 10-20%
• Occasional hesitation on acceleration

Diagnosis

With a live data scanner, check MAF reading at warm idle. Normal values:

• 1.2L engine: 3-6 g/s
• 1.6L engine: 5-8 g/s
• 2.0L engine: 7-12 g/s

A value outside this range, or one that drops sharply under acceleration, confirms P0101.

Fixes

1. MAF sensor cleaning (60% success rate)

👉 CRC MAF sensor cleaner on Amazon UK — £10-14

Steps: unplug MAF, 6-8 sprays on the hot wire, air dry 15 min, refit, clear code.

Do NOT touch the hot wire with a cloth — it will break. Spray only.

2. New air filter

👉 Air filter on Amazon UK — £8-18. Replace every 15-20k miles.

3. Inspect intake hoses

A split hose after the MAF lets in unmeasured air — same effect as a contaminated MAF.

4. Replace MAF sensor

If cleaning doesn't resolve it after 200 miles:

👉 Bosch MAF sensor on Amazon UK — £40-130

Repair cost