Investigating P0100 on Your 2021 Honda HR-V
A P0100 code on your 2021 Honda HR-V means the ECM has detected a malfunction in the mass air flow (MAF) sensor circuit. The 2nd-generation HR-V (2016–2022) uses the 1.8L naturally aspirated four-cylinder engine, which relies on accurate MAF readings for proper fuel control.
Symptoms
- Check engine light on
- Rough or unstable idle
- Hesitation on acceleration
- Reduced power—noticeable on the 1.8L's modest output
- Poor fuel economy
- Possible stalling
Common Causes
- Contaminated MAF sensor (35%) — Oil, dust, and debris on the sensing element after four-plus years.
- Wiring or connector issues (22%) — Heat and vibration affecting connections.
- Faulty MAF sensor (18%) — Internal sensor failure.
- Intake air leak (13%) — Cracked boot or loose clamp.
- Air filter restriction (8%) — Overdue filter change.
- ECM issue (4%) — Rare.
Diagnostic Steps
- MAF sensor cleaning — Remove and clean with dedicated MAF cleaner spray.
- Connector inspection — Check for corrosion or looseness.
- Air filter replacement — Fresh OEM-style paper filter.
- Intake inspection — Check all post-MAF connections.
- Scan tool verification — Confirm MAF values are within spec.
- MAF replacement — If cleaning doesn't resolve the code.
Repair Costs
- MAF cleaning: $10–$15 (DIY)
- Air filter: $12–$25 (DIY)
- MAF sensor: $130–$290
- Intake boot: $65–$175
- Wiring repair: $90–$250
Warranty
Your 2021 HR-V's basic warranty has expired. The federal emissions warranty covers the MAF sensor for 8 years/80,000 miles through 2029. Check mileage with your Honda dealer.