What P0175 Means on Your 2020 Honda Odyssey
The P0175 code on your 2020 Honda Odyssey tells you that bank 2 of the 3.5L V6 engine is running rich — there's more fuel in the combustion mixture than the optimal 14.7:1 air-fuel ratio. The 2020 Odyssey (5th generation) is powered by the J35Y6 3.5L i-VTEC V6 producing 280 hp and 262 lb-ft of torque, paired with Honda's 10-speed automatic transmission. Bank 2 is the rear cylinder bank closest to the firewall, with its own exhaust manifold and O2 sensors.
Symptoms in the Odyssey
- Check engine light on the instrument cluster
- Noticeable fuel smell from exhaust, especially at idle or drive-thru
- Rough idle felt through the vehicle
- Black smoke or soot at the tailpipe
- Fuel economy drops below the rated 19–28 mpg
- Possible engine misfire or stumble
Most Likely Causes
1. O2 Sensor Degradation on Bank 2 (High Likelihood)
At 4-6 years old with potentially 50,000-80,000 miles, the bank 2 upstream O2 sensor on the Odyssey's V6 is a prime suspect. The rear bank sensor is subjected to higher heat due to its proximity to the firewall and reduced airflow. A degraded sensor with slow response or lean bias causes the ECM to add extra fuel, creating an actual rich condition. O2 sensor replacement on bank 2 of the Odyssey is moderately challenging due to access constraints.
2. Leaking Fuel Injector (Medium Likelihood)
The Odyssey's 3.5L V6 uses port fuel injection with individual injectors per cylinder. After years of service, injector O-rings can deteriorate, and the injector pintle may not seal completely. A bank 2 injector that drips fuel continuously enriches that bank. The Odyssey's engine is essentially the same unit used in the Pilot, Ridgeline, and Passport, and injector issues are well-documented. Pull the bank 2 spark plugs — a fuel-fouled plug pinpoints the leaking injector.
3. Fuel Pressure Regulator Malfunction (Medium Likelihood)
The fuel pressure regulator maintains consistent rail pressure for all six injectors. When the internal diaphragm fails, fuel pressure rises above specification, and every injector delivers more fuel per pulse than commanded. The classic diagnostic test: disconnect the vacuum line from the regulator and check for fuel. Also verify fuel rail pressure with a gauge — it should be approximately 47-53 psi at idle with vacuum connected.
4. EVAP System Issue (Low Likelihood)
A purge valve that doesn't close properly or a saturated charcoal canister can introduce excess fuel vapor into the intake manifold. The Odyssey's EVAP system is relatively simple, but after several years, the purge valve solenoid can weaken. If you've habitually topped off the fuel tank, the canister may be saturated with liquid fuel.
Diagnostic Steps
- Read all codes — Check for P0172 (bank 1 rich) alongside P0175. Both codes suggest fuel pressure or MAF issue. P0175 alone points to bank 2-specific problems.
- Compare bank fuel trims — Use a scan tool to compare bank 1 and bank 2 LTFT. A significant split confirms a bank-specific issue.
- Test O2 sensors — Monitor bank 2 upstream sensor response time and voltage pattern.
- Inspect spark plugs — Check bank 2 plugs for fuel fouling.
- Verify fuel pressure — Test at idle, under load, and at key-off to check for regulator failure.
Repair Costs for the 2020 Odyssey
- O2 sensor replacement (bank 2): $130–$310 (rear bank labor premium)
- Fuel injector replacement: $120–$320 per injector
- Fuel pressure regulator: $140–$300
- EVAP purge valve: $80–$200
DIY or Professional?
The Odyssey's engine bay is wider than the CR-V's or Civic's, offering better access. However, bank 2 components are still against the firewall and require extensions and patience. O2 sensor replacement is doable with basic tools but expect corroded threads after 4+ years. Spark plug inspection is an excellent diagnostic step within DIY reach. Fuel injector work on the rear bank requires more expertise and time due to access constraints.
Family Vehicle Considerations
As a family minivan, your Odyssey carries precious cargo. While P0175 isn't immediately dangerous, a rich condition can occasionally cause rough running or hesitation that might catch you off guard in traffic. Address it within two weeks. Also note that the Odyssey's catalytic converters are expensive ($800-$1,800 per bank) and are common theft targets — keeping them healthy by fixing P0175 promptly is wise.