What P0175 Means on Your 2021 Honda Pilot
The P0175 code on your 2021 Honda Pilot indicates that bank 2 of the 3.5L V6 engine is running rich — too much fuel in the combustion mixture. The 2021 Pilot uses Honda's proven J35Y6 3.5L i-VTEC V6 producing 280 hp and 262 lb-ft of torque, paired with either a 6-speed or 9-speed automatic transmission. As a V6, the engine has two distinct cylinder banks, and P0175 specifically identifies that bank 2 (the rear bank, closest to the firewall) is receiving excess fuel.
Symptoms on the Pilot
- Check engine light illuminated
- Strong fuel odor from the exhaust
- Rough or uneven idle, noticeable in the quiet cabin
- Dark exhaust smoke during acceleration
- Fuel economy drops below the rated 19–27 mpg
- Possible misfires or engine stumble
Common Causes for the 2021 Pilot
1. Faulty Bank 2 O2 Sensor (High Likelihood)
The 3.5L V6 has dedicated oxygen sensors for each bank. The bank 2 upstream O2 sensor (sensor 1) is the primary fuel control sensor for that bank. If it reads falsely lean — due to contamination, wiring damage, or internal degradation — the ECM responds by adding fuel, creating an actual rich condition. On the 2021 Pilot, the bank 2 sensor sits on the rear exhaust manifold and can be more difficult to access. Use a scan tool to monitor sensor response time and voltage patterns.
2. Leaking Fuel Injector on Bank 2 (Medium Likelihood)
The 2021 Pilot's 3.5L V6 uses port fuel injection with individual injectors for each cylinder. Bank 2 injectors (cylinders 1, 2, 3 on the rear bank) can develop seal leaks after a few years of service. A leaking injector drips fuel when it should be closed, enriching that bank. Inspect the spark plugs on bank 2 cylinders — a wet, fuel-fouled plug identifies the problematic injector. The J35 engine's injectors are reliable but not immune to O-ring degradation.
3. Fuel Pressure Regulator Issue (Medium Likelihood)
The fuel pressure regulator on the Pilot's 3.5L maintains consistent fuel rail pressure. Over time, the internal diaphragm can deteriorate, causing fuel pressure to creep up. Higher fuel pressure means every injector delivers slightly more fuel per pulse. Check for fuel in the regulator's vacuum line — a wet line is diagnostic of a failed diaphragm. Also verify fuel rail pressure against Honda's specifications (approximately 47-53 psi at idle).
4. Dirty MAF Sensor (Low Likelihood)
A contaminated MAF sensor that overreads airflow causes excess fuel injection across both banks. However, since P0175 is bank 2-specific, a MAF issue would typically trigger both P0172 and P0175 simultaneously. Clean the MAF sensor as part of routine diagnostics, but focus on bank 2-specific causes first.
Diagnostic Approach
- Check for companion codes — P0172 (bank 1 rich) alongside P0175 suggests a systemic issue. P0175 alone points to a bank 2-specific problem.
- Monitor fuel trims — Compare bank 1 and bank 2 LTFT values. A significant difference confirms a bank-specific issue.
- Test O2 sensors — Compare bank 1 and bank 2 sensor waveforms for differences in response time or bias.
- Inspect bank 2 spark plugs — Remove plugs from the rear bank and check for fuel fouling.
- Check fuel pressure — Verify regulator performance and look for fuel in the vacuum line.
Repair Costs for the 2021 Pilot
- O2 sensor replacement (bank 2): $120–$300 (rear bank access adds labor time)
- Fuel injector replacement: $120–$350 per injector (bank 2 is harder to access)
- Fuel pressure regulator: $150–$320
- MAF sensor replacement: $90–$230
DIY Considerations
The Pilot's engine bay provides decent access to bank 1 (front) components but bank 2 (rear) is significantly harder to reach. The rear bank O2 sensor requires working from underneath or removing the intake manifold. Bank 2 spark plugs are accessible but cramped. For DIYers, MAF cleaning and fuel pressure testing are straightforward. Bank 2 O2 sensor and injector work may be worth paying a shop to handle due to accessibility challenges.
Driving With P0175
You can drive your Pilot with P0175 for daily commuting, but address it within two weeks. The 3.5L V6's catalytic converters are expensive to replace ($800-$2,000 per bank), and running rich accelerates catalyst degradation. The rear bank converter is especially costly due to labor access. Fixing P0175 now prevents a much larger expense later.