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All codes › P0174 › 2017 Honda Civic

P0174 on a 2017 Honda Civic

Fuel System Too Lean (Bank 2)

Severity: moderate Safe to drive (short term) Compact Sedan 2015-2019 Honda Civic

What does P0174 mean on a 2017 Honda Civic?

P0174 is the Bank 2 counterpart of P0171. It is set when the engine control module sees long-term fuel trim on Bank 2 driven beyond approximately +25 %. The ECM is adding the maximum allowed amount of fuel and the Bank 2 oxygen sensor still reports lean. Because P0174 only applies to V-engines and engines with separate exhaust banks, whether P0174 appears alongside P0171 tells you a lot about the root cause.

Symptoms on a 2017 Honda Civic

Likely causes on a 2017 Honda Civic

  1. Vacuum leak specific to Bank 2 (intake gasket, vacuum tee, brake-booster tee) Most common
    Estimated repair: $80– $600
  2. Cracked plastic intake manifold on V-engines (common on Ford and Chrysler V6/V8s) Common
    Estimated repair: $250– $900
  3. Bank 2 fuel injectors clogged or under-delivering Common
    Estimated repair: $150– $1,200
  4. Bank 2 upstream O2 sensor lazy or biased lean Common
    Estimated repair: $150– $450
  5. Bank 2 exhaust leak upstream of the front O2 sensor Occasional
    Estimated repair: $100– $500
  6. Weak fuel pump or clogged filter (both banks lean — P0171 also present) Occasional
    Estimated repair: $80– $900
  7. PCV system fault drawing extra air into Bank 2 Occasional
    Estimated repair: $30– $200

How to diagnose this on a 2017 Honda Civic

  1. Determine whether P0171 is also present

    Pull all codes. If P0174 sets alone, the cause is on Bank 2 specifically — an intake leak on that side, injectors on that side, or the Bank 2 O2 sensor. If P0171 and P0174 set together, the cause is something affecting the whole engine: low fuel pressure, MAF issue, large vacuum leak.

    Tools: Scan tool

  2. Identify the Bank 2 side of the engine

    On most transverse V6s Bank 2 is the bank closest to the radiator. On Ford modular V8s Bank 2 is the passenger side. On GM truck V8s Bank 2 is the passenger side. Confirm in the service manual before pulling parts.

    Tools: Vehicle-specific service information

  3. Smoke-test the Bank 2 intake side

    With smoke in the intake, focus on the Bank 2 intake runner gaskets, the vacuum lines that feed Bank 2 specifically, and the brake booster line if it tees into Bank 2. Cracked plastic intake manifolds on Ford 4.6 V8s, Chrysler 4.0 inline-6, and several GM engines are classic Bank-2-specific P0174 causes.

    Tools: EVAP / intake smoke machine, Flashlight and mirror

  4. Compare Bank 1 vs Bank 2 fuel trims

    With the engine warm, read Bank 1 LTFT and Bank 2 LTFT simultaneously. A 10 %+ difference between banks isolates the problem to the bank with the higher positive number.

    Tools: Scan tool with multi-PID display

  5. Test Bank 2 injectors for low flow

    Run the scan tool injector balance test on Bank 2 injectors only. An injector that does not produce as much pressure drop as its peers is under-delivering fuel and causing the bank-specific lean condition.

    Tools: Scan tool with injector balance

Known Technical Service Bulletins for the 2015-2019 Honda Civic

Manufacturers publish Technical Service Bulletins (TSBs) when a known issue affects a specific vehicle. These bulletins come from the NHTSA database for your Honda Civic.

+14 more TSBs available in MECH AI's TSB explorer for this vehicle.

Common fixes

About the 2015-2019 Honda Civic

The 2015-2019 Honda Civic was commonly sold with the following powertrains: 2.0L I4, 1.5L Turbo I4, 1.8L I4. Common trims include LX, Sport, EX, Touring.

P0171 + P0174 together vs. P0174 alone

The presence pattern is your best diagnostic clue:

Why cracked intake manifolds are so common

Plastic intake manifolds began appearing in the mid-1990s for weight and heat-soak benefits. Two decades of thermal cycling has caused many of them to crack — particularly Ford 4.6 V8 (cracked coolant passage near the EGR tube), Chrysler 4.0 inline-6 (rear of the manifold), and GM 3.6 V6. The crack is often invisible to the eye and only shows up under smoke pressure.

Driving with P0174 long-term

Like P0171, mild long-term lean operation does not destroy the engine quickly, but sustained lean conditions raise combustion temperatures. The risks build over months: pinged spark plug electrodes, eventual catalyst damage, and burnt exhaust valves on the affected bank. Fix P0174 within a few weeks rather than letting it ride for a year.

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