OBD codes / P0174 / Toyota RAV4
P0174 on a Toyota RAV4
System Too Lean (Bank 2)
3.5L 2GR-FE V6 only; bank 2 is the firewall side.
What P0174 usually means on a RAV4
P0174 is the bank 2 version of a lean code and only appears on V6 RAV4s. It signals that the rear cylinder bank is running lean. When it shows up on its own, look for something specific to that bank — a cracked rear PCV hose or a leaking rear intake gasket. When it pairs with P0171, the cause is usually shared across both banks, like a dirty MAF or low fuel pressure.
Most likely causes on this model
- Bank 2 vacuum leak
A cracked rear PCV line or leaking rear intake gasket leans only the firewall-side bank.
- Dirty MAF (with P0171)
When both banks read lean, a contaminated MAF is the shared cause.
- Failing bank 2 AF sensor
The rear Denso sensor is often original and slows with age.
- Low fuel pressure
A weak pump leans both banks under load, so check pressure if trims climb everywhere.
What it costs on a RAV4
A standalone P0174 means hunting a rear-bank vacuum leak, which is fiddly because the hoses hide behind the intake, so budget for diagnostic time. A shared cause with P0171 is usually cheaper to isolate. A smoke test is the quickest path to the leak.
Year, engine and mileage change the answer. Get a diagnosis for your RAV4 — it weighs these causes against your exact configuration and real complaint data.
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Based on widely reported patterns for this model; individual causes vary by year, engine and history. Generic P0174 behavior is covered on the main P0174 page. Confirm with a scan tool before buying parts.