OBD codes / P0174 / Toyota Tacoma
P0174 on a Toyota Tacoma
System Too Lean (Bank 2)
4.0L 1GR-FE V6 and 3.5L 2GR-FKS V6; bank 2 is the second cylinder bank.
What P0174 usually means on a Tacoma
P0174 is the bank 2 lean code and shows up only on V6 Tacomas. It means the second cylinder bank is running lean. On its own it usually points to a vacuum leak specific to that bank, such as a cracked PCV line or leaking intake gasket. When it comes with P0171, the cause is generally shared between banks — a dirty MAF or low fuel pressure.
Most likely causes on this model
- Bank 2 vacuum leak
A cracked hose or leaking gasket on the second bank leans only that side.
- Dirty MAF (with P0171)
If both banks go lean together, a dirty MAF is the common denominator.
- Failing bank 2 AF sensor
The rear bank's Denso sensor is frequently the original unit and slows down over time.
- Low fuel pressure
A failing pump leans both banks under load, so measure fuel pressure if trims rise across the board.
What it costs on a Tacoma
A standalone P0174 usually means hunting a bank 2 vacuum leak, which takes diagnostic time on the V6. A cause shared with P0171 is easier to isolate. A smoke test is the fastest route to the leak.
Year, engine and mileage change the answer. Get a diagnosis for your Tacoma — 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.