| Table of Contents | |
| Possible Causes of P0174 & Their Repair Costs | Code P0174 means the engine’s Bank 2 is running too lean, with too much air or insufficient fuel in the air-fuel mixture. |
| How to Diagnose the Cause of Your P0174 Code | Several issues can trigger a P0174 code, including vacuum leaks, faulty mass airflow sensors, clogged fuel injectors, problematic oxygen sensors, or fuel pressure regulator issues. |
| You can drive briefly with a P0174 code, but it’s not recommended long term. Prolonged driving may cause damage and pose safety risks, so fix the issue promptly. | |
| DIY | How To Fix P0174 Causes |
DIYable P0174 triggers include:
|
| P0174 Code FAQs |
Frequently asked questions:
|
A P0174 diagnostic trouble code (DTC): System Too Lean (Bank 2) occurs when the engine control module (ECM) or powertrain control module (PCM) detects that the engine is receiving too much oxygen or not enough fuel. This creates a lean condition, throwing off the ideal (for most engines) 14.7 parts oxygen to 1 part fuel ratio. This code also tells us that the problem is concentrated on Bank 2 of the engine.
A similar DTC, P0171, indicates a lean fuel condition in Bank 1. Codes P0172 (Bank 1) and P0175 (Bank 2) signal an opposite condition, System Too Rich. Codes P0170 (Bank 1) and P0173 (Bank 2) refer to fuel trim malfunction or the combustion chamber not receiving the correct amount of fuel.
As covered, a P0174 code indicates an air-fuel mixture imbalance in engine Bank 2. Understanding engine bank configurations can help diagnose the issue more efficiently.
In V6 or V8 engines, Bank 2 typically starts with Cylinder #2, opposite the side of Cylinder #1. Most automakers use odd-numbered cylinders on one bank and even-numbered on the other, though Ford uses sequential numbering.
Inline engines also use two banks, with Bank 2 usually comprising the second grouping of two or three cylinders. Boxer or “flat” engines in some Subarus and Porsches follow a Bank 1/Bank 2 system similar to V-formation engines.
Identifying Bank 2 can streamline the diagnosis by narrowing the focus to specific components, such as fuel injectors and oxygen sensors serving that bank’s cylinders.
Code P0174-related issues usually impact engine performance, resulting in hesitation, stalling, and rough idling. These conditions don’t usually require you to stop driving, but you’ll want to resolve the problem over the next few days (not weeks) to avoid damaging critical components.
Keep reading for a deep dive into P0174 codes, which include causes, symptoms, repairs, and the makes and models most likely to have these problems.
Possible Causes of P0174 & Their Repair Costs
Continued driving with a P0174 code risks damage to the pistons, cylinder walls, valves, and catalytic converter. So, you’ll want to zero in on the problem right away or have a mechanic do the work.
Check out the FIXD article on the most common causes of check engine lights.
Here’s a look at average standalone prices for the components usually involved in repairing P0174-related issues. We’ve included what a mechanic will likely charge for the complete job. Prices can vary, depending on what you drive and where you live.
P0174 Code Triggers & Typical Repair Costs
| Part To Repair | Part / DIY Price | Mechanic Total Cost |
| Vacuum Line | $50–$100 | $200–$300 |
| Mass Air Flow (MAF) Sensor: Clean | $20–$40 | $100–$200 |
| Mass Air Flow (MAF) Sensor: Replace | $40–$50 | $239–$346 |
| Exhaust: Repair Leak (welding) | N/A | $100–$200 |
| Fuel Filter | $87–$100 | $175–$211 |
| Fuel Pressure Regulator | $165–$195 | $266–$322 |
| Oxygen Sensor | $300–$333 | $362–$412 |
| Fuel Injector | $450–$541 | $644–$784 |
| Fuel Pump | $923–$1,056 | $1,089–$1,266 |
Here’s how troublesome parts can cause a P0174 code.
Parts Most Likely to Fail & Cause a P0174 Code
| Parts that can cause P0174 | How it could cause P0174 |
| Vacuum Line MAF Sensor Exhaust Oxygen Sensor |
Introduces too much air into the combustion process, creating an imbalance in the correct air-to-fuel ratio. |
| Fuel Filter Fuel Pressure Regulator Fuel Injector Fuel Pump |
Disrupts the normal combustion cycle by limiting the amount of fuel. |
Makes Commonly Affected By P0174
According to FIXD sensor data, no major automotive brand is exempt from check engine lights caused by a code P0174. Nevertheless, some brands are more vulnerable to this issue than others.
This fact starts with the stalwart Ford F-150. It’s a top-of-the-list entry, followed by the Expedition SUV and the storied Mustang. The F-150 and Expedition share a platform and many components, so it’s unsurprising that both vehicles have similarly high occurrence ratings for P0174 codes.
Meanwhile, the Altima represents Nissan’s only model with a high incident level of P0174 codes. The Maxima and Murano sit in the middle range.
Chevrolets takes third place. Like Ford, the Silverado 1500 is the most likely Chevy to experience a P0174 code. And like its Detroit rival, the Silverado’s Tahoe platform mate also has a history with this DTC. However, the Tahoe’s occurrence rate is medium, while the Silverado has a high rating. The Impala completes the automaker’s trio for P0174 codes.
Toyota’s experience with P0174 codes cuts across a wide array of the company’s models, starting with the long-running Camry sedan. This sedan is followed by the automaker’s Sienna minivan and the Highlander crossover. Despite the different body styles, all three models share a version of the same platform and rely on the same engine architecture, which explains the commonality of P0174-related issues.
GMC completes the code P0174 top five list, with the Sierra pickup getting the top spot. Its Tahoe derivative, the Yukon, slides into third, while the Acadia crossover sits between them in second place.
| Top 5 Makes Affected by P0174 | Most Affected Model(s) |
Ford | F-150 |
| Expedition | |
| Mustang | |
Nissan | Altima |
| Maxima | |
| Murano | |
Chevrolet | Silverado 1500 |
| Tahoe | |
| Impala | |
Toyota | Camry |
| Sienna | |
| Highlander | |
GMC | Sierra |
| Acadia | |
| Yukon |
How to Diagnose the Cause of Your P0174 Code
Diagnosing a check engine light starts with using an OBD-II scanner to identify what’s causing the issue. The FIXD plug-in sensor will show the code and likely causes on your phone via the accompanying FIXD app. You can also try a basic code reader with a cable to plug into the car’s OBD-II port. In truth, there are only a few things a novice DIYer can do to identify what triggered a P0174 code. You’ll want a flashlight, gloves, safety goggles, and a rag to get started. A more involved effort will require essential hand tools.
Safety Essentials
Before exploring the source of a P0174 code, you’ll want to observe the following:
- Park on a level surface in a safe area
- Ensure the car is off and the parking brake is engaged
- Allow the engine to cool
Symptoms of P0174 Causes
Most repairs for a P0174-related problem involve at least a modest amount of mechanical skill (DIY suggestions are covered below). However, checking for symptoms is something just about any car owner can do. Isolating the trouble can speed up repairs, regardless of who’s doing the work.
Click on each Possible Cause of a P0174 code to know the symptoms to look out for and what to inspect.
Symptoms:
- Illuminated check engine light
- Higher-than-normal engine RPMs at idle
- Rough engine idle
- Engine sputtering or stalling
- Hard-to-start engine
- Abrupt transmission shifts at high RPMs
What to Inspect:
Check air hoses and vacuum lines:
- Look for cracks or wear
- Listen for hissing sounds with the engine running
- Spray water on hoses, lines, gaskets, and injectors—engine sputtering may indicate a leak
Symptoms:
- Hesitation or jerking during acceleration
- Higher-than-normal engine RPMs at idle
- Rough engine idle
- Engine sputtering or stalling
- Hard-to-start engine
- Abrupt transmission shifts at high RPMs
What to Inspect:
Check the MAF sensor’s wiring connection for tightness, damage, or dirt. If necessary, a technician can perform further diagnostics to address the P0174 code.
Symptoms:
- Illuminated check engine light
- Reduced fuel economy
- Engine hesitation
- Unusual engine noise
- Burning smell or unusual odor
- Gas pedal vibration
What to Inspect:
Inspect exhaust components for cracks, damage, or soot buildup. Be watchful for fumes or gas smells in the engine bay or cabin. If issues are found, consult a trained exhaust technician to address the P0174 code.
Symptoms:
- Illuminated check engine light
- Rough idling
- Reduced fuel economy
- Engine stalling or hesitation
- Black exhaust smoke
- Failed emissions test
What to Inspect:
An intermediate DIYer or a technician can use a voltmeter to test the status of an oxygen sensor.
Symptoms:
- Illuminated check engine light
- Reduced fuel economy
- Engine hesitation or stalling
- Engine misfiring
- Reduced acceleration (particularly while under load or ascending a hill)
What to Inspect:
A DIYer with intermediate skills and familiarity with working around gasoline can remove the fuel filter for inspection or replacement. Otherwise, let a mechanic handle the problem.
Symptoms:
- Illuminated check engine light
- Rough idling
- Engine stalling or hesitation
- Black exhaust smoke
- Gas in the regulator vacuum line
- Engine cranks but doesn’t start
What to Inspect:
Requires intermediate DIY skills or a professional mechanic and a fuel pressure tester.
Symptoms:
- Illuminated check engine light
- Rough idling
- Engine stalling or hesitation
- Fuel leak/smell
- Black exhaust smoke
What to Inspect:
- Locate Bank 2 fuel injectors
- Start the engine
- Use a long screwdriver:
- Place the tip on an injector
- Put an ear on the screwdriver handle
- Listen for clicking sounds
- No clicking may indicate a clogged or faulty injector
For further testing (by an experienced DIYer or mechanic):
- Disconnect injectors one at a time while the engine runs
- If engine sound/RPM doesn’t change, that injector may be faulty
Symptoms:
- Illuminated check engine light
- Rough idling
- Reduced fuel economy
- Engine stalling or hesitation
- Hard-to-start engine
- Whirring noise from the fuel tank area
- Overheating
What to Inspect:
Requires intermediate DIY skills or a professional mechanic and a fuel pressure tester. Additional electrical testing may be required.
Can I drive with Code P0174?
Quick answer: Yes, driving with a P0174 code is okay, but don’t delay repairs beyond a few days—this is a problem with moderate severity.
Assuming the affected car isn’t becoming difficult to drive (due to stalling or hesitation), you can drive it for a couple of days but resolve the problem within a week to prevent internal engine or catalytic converter damage.
That said, any performance loss should be dealt with immediately due to the inherent safety risks of reduced power while driving on a highway or crossing an intersection. In this situation, towing the car is far safer than driving to the repair shop.
Here’s a more detailed look at driveability with a P0174 code.
| Causes | Can I Drive? | Risks / Safety / Performance |
|---|---|---|
|
Vacuum Leak |
It’s okay to drive for a short time, but get the issue fixed soon. Avoid driving if you notice any performance problems, as this could be unsafe. |
Prolonged driving with a P0174 code can harm important engine parts and other vital components. The risk of stalling or hesitation also makes it dangerous to drive for long periods. |
|
Faulty Mass Air Flow (MAF) Sensor |
It’s okay to drive for a short time, but get the issue fixed soon. Avoid driving if you notice any performance problems, as this could be unsafe. |
Prolonged driving with a P0174 code can harm important engine parts and other vital components. The risk of stalling or hesitation also makes it dangerous to drive for long periods. |
|
Exhaust Leak |
It’s okay to drive for a short time, but get the issue fixed soon. Avoid driving if you notice any performance problems, as this could be unsafe. |
Prolonged driving with a P0174 code can harm important engine parts and other vital components. The risk of stalling or hesitation also makes it dangerous to drive for long periods. |
|
Faulty Oxygen Sensor |
It’s okay to drive for a short time, but get the issue fixed soon. Avoid driving if you notice any performance problems, as this could be unsafe. |
Prolonged driving with a P0174 code can harm important engine parts and other vital components. The risk of stalling or hesitation also makes it dangerous to drive for long periods. |
|
Defective Fuel Filter |
It’s okay to drive for a short time, but get the issue fixed soon. Avoid driving if you notice any performance problems, as this could be unsafe. |
Prolonged driving with a P0174 code can harm important engine parts and other vital components. The risk of stalling or hesitation also makes it dangerous to drive for long periods. |
|
Bad Fuel Pressure Regulator |
It’s okay to drive for a short time, but get the issue fixed soon. Avoid driving if you notice any performance problems, as this could be unsafe. |
Prolonged driving with a P0174 code can harm important engine parts and other vital components. The risk of stalling or hesitation also makes it dangerous to drive for long periods. |
|
Damaged Fuel Injector |
It’s okay to drive for a short time, but get the issue fixed soon. Avoid driving if you notice any performance problems, as this could be unsafe. |
Prolonged driving with a P0174 code can harm important engine parts and other vital components. The risk of stalling or hesitation also makes it dangerous to drive for long periods. |
|
Defective Fuel Pump |
It’s okay to drive for a short time, but get the issue fixed soon. Avoid driving if you notice any performance problems, as this could be unsafe. |
Prolonged driving with a P0174 code can harm important engine parts and other vital components. The risk of stalling or hesitation also makes it dangerous to drive for long periods. |
DIY | How To Fix P0174 Causes
As mentioned, most P0174-related repairs require a modest amount of skill, limiting DIY involvement. However, there is some work that a novice can attempt to take on.
Just remember to recognize your limits when attempting DIY repairs. Be aware of any steps that might cause injury or damage, and don’t hesitate to seek help from a professional mechanic.
Possible Cause: Vacuum Leak
What is it?
Proper air-fuel mixture is one vital element of a smooth-running engine. A vacuum leak creates an imbalance that can lead to a higher-revving engine and code P0174.
How hard is it to fix?
Difficulty Level: Moderate
The greatest challenge to fixing a vacuum leak is finding the problem. The water spray technique (see above) only goes so far and can require more sophisticated methods that are best left to experienced hands. While replacing some vacuum lines is relatively easy, a vacuum leak involving a gasket, intake manifold, or other components requires professional intervention.
Cost of Repairs
Depending on the vehicle and the component, a replacement vacuum line will cost $50 to $150.
Possible Cause: Faulty MAF Sensor
What is it?
The mass air flow (MAF) sensor measures the amount of air entering the engine, which determines how much fuel is sent into the combustion chamber. A dirty or defective MAF sensor affects this reading.
How hard is it to fix?
Difficulty Level: Moderate
Accessing the MAF sensor is uncomplicated in most cars, but if a replacement is involved, it requires a delicate touch and very specific steps.
Cost of Repairs
Expect to pay $20 to $40 for MAF sensor cleaner spray and supplies. A new MAF sensor costs $40 to $50.
Other DIY Considerations for Code P0174
The actual work of replacing components like an oxygen sensor or fuel filter is straightforward. However, the challenge often lies in accessing the components. A novice DIYer without discipline and patience will find these tasks frustrating. Yet, someone with reasonable mechanical skills who doesn’t mind working under a car or first removing other components will find fixing a P0174-related issue ultimately rewarding.
Before dealing with any code P0174-related repair, check whether your car is under warranty. You can save money by letting the automaker handle the work. In addition, research if there are any technical service bulletins (TSBs) for your car. TSBs are official repair/correction notices issued by the manufacturer that cover specific problem areas. You can research this online or contact a dealer.
P0174 Code FAQs
What makes and models does code P0174 affect the most?
Here’s a breakdown of the vehicles most affected by code P0174, according to FIXD sensor data collected in 2023.
| Make | Model | Occurrence Frequency |
| Chevrolet | Silverado 1500 | High |
| Ford | F-150 | High |
| Ford | Expedition | High |
| Nissan | Altima | High |
| Toyota | Camry | High |
| BMW | X5 | Medium |
| Cadillac | Escalade | Medium |
| Cadillac | SRX | Medium |
| Chevrolet | Tahoe | Medium |
| Chevrolet | Impala | Medium |
| Chevrolet | Traverse | Medium |
| Ford | Mustang | Medium |
| Ford | Ranger | Medium |
| GMC | Sierra | Medium |
| GMC | Acadia | Medium |
| GMC | Yukon | Medium |
| Honda | Pilot | Medium |
| Nissan | Maxima | Medium |
| Nissan | Murano | Medium |
| Toyota | Sienna | Medium |
| Toyota | Highlander | Medium |
How can I prevent P0174 from occurring?
While you can’t completely prevent P0174 from occurring, regular vehicle maintenance can help reduce the risk. These tasks include:
- Routine inspections of air and fuel system components
- Timely replacement of air and fuel filters
- Regular oil and filter changes
- Addressing any performance issues promptly
However, even with proper maintenance, P0174 can still occur due to normal wear and tear or unexpected component failures.
What causes code P0174?
Code P0174 indicates the engine is running too lean (too much air or too little fuel) in Bank 2. Common causes include:
- Vacuum Leak
- Faulty Mass Air Flow (MAF) Sensor
- Exhaust Leak
- Faulty Oxygen Sensor
- Defective Fuel Filter
- Bad Fuel Pressure Regulator
- Damaged Fuel Injector
- Defective Fuel Pump
These issues disrupt the air-fuel balance, leading to poor engine performance and potential damage if left uncorrected.
How much does it cost to fix code p0174?
The cost to fix code P0174 varies widely depending on the underlying cause, ranging from around $20 for minor issues like cleaning the mass air flow (MAF) sensor to over $1,200 for replacing the fuel pump. Actual costs depend on your specific vehicle, the parts needed, and local labor rates, so a proper diagnosis is essential for an accurate estimate.
References:
Repair-cost estimates, repairpal.com (various dates). Retrieved August 19, 2024, from repairpal.com.
Dave Goldberg is an automotive journalist and lifelong car fanatic. He writes for numerous enthusiast and business outlets and is an ongoing contributor to HotCars.com, one of the most popular car culture websites. When he’s not writing or driving, Dave is either under a hood or asleep. His credentials include a BA in Journalism from The George Washington University.
