P0174 on a 2012 Nissan Altima
Fuel System Too Lean (Bank 2)
P0174 on a 2012 Nissan Altima indicates fuel system too lean (bank 2). It usually stays drivable short-term but should be diagnosed promptly. The most common cause is vacuum leak specific to bank 2 (intake gasket, vacuum tee, brake-booster tee) (typically $80–$600). Confirm the root cause before replacing parts.
What does P0174 mean on a 2012 Nissan Altima?
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.
This guide covers P0174 across the 2010-2014 Nissan Altima generation — the symptoms, causes, and diagnostic steps below apply to every model year from 2010 through 2014.
Is it safe to drive a 2012 Nissan Altima with P0174?
In most cases a 2012 Nissan Altima stays drivable for short trips with P0174 active, but diagnose and repair it promptly. This is a moderate-severity code — ignoring it can lead to further damage or a failed emissions test.
What are the symptoms of P0174 on a 2012 Nissan Altima?
- Check Engine Light is illuminated
- Rough idle, especially when cold
- Hesitation or stumble on light acceleration
- Reduced fuel economy
- Mild power loss
- Possible whistling vacuum-leak sound
What causes P0174 on a 2012 Nissan Altima?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Vacuum leak specific to Bank 2 (intake gasket, vacuum tee, brake-booster tee) | Most common | $80–$600 |
| Cracked plastic intake manifold on V-engines (common on Ford and Chrysler V6/V8s) | Common | $250–$900 |
| Bank 2 fuel injectors clogged or under-delivering | Common | $150–$1,200 |
| Bank 2 upstream O2 sensor lazy or biased lean | Common | $150–$450 |
| Bank 2 exhaust leak upstream of the front O2 sensor | Occasional | $100–$500 |
| Weak fuel pump or clogged filter (both banks lean — P0171 also present) | Occasional | $80–$900 |
| PCV system fault drawing extra air into Bank 2 | Occasional | $30–$200 |
How to diagnose this on a 2012 Nissan Altima
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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
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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
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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
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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
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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
NHTSA complaints & recalls for the 2012 Nissan Altima
Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2012 Nissan Altima. Use these to gauge how common a problem is on your specific vehicle before you start chasing Nissan Altima diagnostics.
- POWER TRAIN 149
- ENGINE 68
- VEHICLE SPEED CONTROL 49
- UNKNOWN OR OTHER 56
- AIR BAGS 56
4 active recalls
- AIR BAGS:SIDE/WINDOW Feb 2012
NISSAN IS RECALLING CERTAIN MODEL YEAR 2012 ALTIMA AND VERSA VEHICLES. THESE VEHICLES MAY BE EQUIPPED WITH SIDE CURTAIN AIR BAGS THAT CONTAIN AN INCORRECT PROPELLANT MIXTURE FOR THE INITIATOR COMPONENT USED, RESULTING IN INSUFFICIENT OUTPUT OF COMPRESSED GAS.…
NHTSA campaign 12V055000 - AIR BAGS:FRONTAL:SENSOR/CONTROL MODULE-INACTIVE Aug 2011
NISSAN IS RECALLING CERTAIN MODEL YEAR 2012 NISSAN ALTIMA VEHICLES MANUFACTURED FROM JUNE 15, 2011, THROUGH JUNE 21, 2011 AND MODEL YEAR 2012 NISSAN NV VEHICLES MANUFACTURED FROM JUNE 23, 2011, THROUGH JUNE 28, 2011 BECAUSE THE AIR BAG CONTROL UNIT (ACU) WAS ASSEMBLED INCORRECTLY…
NHTSA campaign 11V408000 - STEERING Oct 2012
Nissan is recalling certain model year 2012-2013 Altima vehicles manufactured from May 10, 2012, through July 26, 2012. These vehicles may have been equipped with transverse link bolts and power steering rack bolts that were not torqued to proper specification.…
NHTSA campaign 12V494000 - SUSPENSION Jul 2011
NISSAN IS RECALLING CERTAIN MODEL YEAR 2011-2012 NISSAN ALTIMA SEDAN VEHICLES MANUFACTURED FROM APRIL 25, 2011, THROUGH JUNE 10, 2011 AT THE CANTON, MISSISSIPPI PLANT. THE TRANSVERSE LINK BOLT MAY NOT HAVE BEEN TORQUED TO THE PROPER SPECIFICATION. THIS CONDITION COULD CAUSE THE…
NHTSA campaign 11V371000
How do I fix P0174 on a 2012 Nissan Altima?
- Repair Bank 2 vacuum / intake leaks
- Replace cracked plastic intake manifold (model-specific)
- Clean or replace Bank 2 fuel injectors
- Replace the Bank 2 upstream O2 sensor
- Repair Bank 2 exhaust leaks
About the 2010-2014 Nissan Altima
The 2010-2014 Nissan Altima was commonly sold with the following powertrains: 2.5L I4, 2.0L VC-Turbo I4, 3.5L V6. Common trims include S, SV, SR, SL, Platinum.
P0171 + P0174 together vs. P0174 alone
The presence pattern is your best diagnostic clue:
- Both P0171 and P0174 active → systemic problem affecting both banks. Check the MAF, fuel pressure, large vacuum leaks (brake booster, PCV hose, throttle body gasket), and the common air intake.
- Only P0174 active → Bank-2-specific problem. Inspect Bank 2 intake gaskets, Bank 2 injectors, Bank 2 O2 sensor, and Bank 2 exhaust upstream of the front sensor.
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.
P0174 on a 2012 Nissan Altima: frequently asked questions
What does diagnostic trouble code P0174 mean on a 2012 Nissan Altima?
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.
What are the symptoms of P0174 on a 2012 Nissan Altima?
Check Engine Light is illuminated. Rough idle, especially when cold. Hesitation or stumble on light acceleration. Reduced fuel economy. Mild power loss. Possible whistling vacuum-leak sound
What causes P0174 on a 2012 Nissan Altima?
Vacuum leak specific to Bank 2 (intake gasket, vacuum tee, brake-booster tee) (most-common). Cracked plastic intake manifold on V-engines (common on Ford and Chrysler V6/V8s) (common). Bank 2 fuel injectors clogged or under-delivering (common). Bank 2 upstream O2 sensor lazy or biased lean (common). Bank 2 exhaust leak upstream of the front O2 sensor (occasional). Weak fuel pump or clogged filter (both banks lean — P0171 also present) (occasional). PCV system fault drawing extra air into Bank 2 (occasional)
Is it safe to drive a 2012 Nissan Altima with P0174?
In most cases a 2012 Nissan Altima stays drivable for short trips with P0174 active, but it should be diagnosed and repaired promptly — this is a moderate-severity code. Ignoring it can lead to further damage or a failed emissions test.