What is an OBD2 code?

An OBD2 (On-Board Diagnostics) code is a diagnostic trouble code (DTC) generated by your vehicle's computer system when it detects a problem. These codes help identify specific issues with your vehicle's engine, transmission, emissions, or other systems.

How do I read OBD2 codes?

To read OBD2 codes, you'll need an OBD2 scanner. Plug it into your vehicle's OBD2 port (usually located under the dashboard), turn your key to the 'ON' position, and follow your scanner's instructions to retrieve the codes. Each code starts with a letter (P, B, C, or U) followed by four numbers.

What do the different types of OBD2 codes mean?

OBD2 codes are categorized by their first letter: P (Powertrain) for engine and transmission issues, B (Body) for interior systems like airbags, C (Chassis) for mechanical systems like brakes, and U (Network) for computer and module communication problems.

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Home » OBD2 Codes » P0174

Code P0174

Symptoms

• Check Engine Light is on

• Poor fuel economy

• Engine misfires

Common Causes

• Vacuum leaks

• Faulty mass air flow (MAF) sensor

• Clogged fuel injectors

Glossary

ECM: Engine Control Module

MAF: Mass Air Flow

Related Codes

• P0171

• P0175

Official description

System Too Lean Bank 2

Laymans terms

Your car's engine is not getting enough fuel on one side, so it's like trying to run with not enough energy.

Explanation

The engine control module (ECM) has detected that the air-fuel mixture on bank 2 is too lean, meaning there is too much air and not enough fuel.

Technical description

The P0174 code indicates that the ECM has detected a lean condition on bank 2. This means the oxygen sensor has detected that the air-fuel ratio is too lean, which could be due to a variety of factors including a vacuum leak, faulty fuel injector, or a problem with the mass air flow sensor.

Diagnosis steps

• Check for vacuum leaks

• Inspect the mass air flow sensor

• Test the fuel injectors

Repair procedures

• Repair any vacuum leaks

• Clean or replace the mass air flow sensor

• Clean or replace fuel injectors

Tools required

• OBD-II scanner

• Vacuum gauge

• Multimeter

Estimated repair cost

$150 - $500

Difficulty level

Moderate

Commonly affected vehicles

• Ford F-150

• Chevrolet Silverado

• Toyota Camry

Preventive measures

• Regularly clean the mass air flow sensor

• Perform routine maintenance on fuel injectors

• Check for vacuum leaks periodically

Error code type

Engine Performance

User experience recommendations

• Do not ignore the Check Engine Light

• Get a professional diagnosis if unsure

• Regular maintenance can prevent this issue

Warranty information

Check your vehicle's warranty for coverage on fuel system components.

Historical data

P0174 has been a common code for vehicles with aging fuel systems or air intake components.

Urgency level

Moderate – It may not cause immediate damage but can lead to poor performance and increased emissions.

Legal and safety notice

Driving with a lean condition can cause increased emissions and may not pass emissions testing.

Testing conditions

• Engine at operating temperature

• Vehicle in closed-loop mode

Component location

Bank 2 refers to the side of the engine opposite bank 1, often the passenger side in a V-type engine.

FAQs

Q: Can I drive with a P0174 code?
A: It's possible, but it's not recommended as it can lead to poor performance and increased emissions.

Q: What happens if I ignore a P0174 code?
A: Ignoring it can lead to engine damage over time due to running too lean, and it may cause your vehicle to fail emissions tests.

Last updated: Oct 28, 2025 • Source: internal database

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