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.

🖨️

Home » OBD2 Codes » P1140

Code P1140

Symptoms

• Check Engine Light is on

• Poor fuel economy

• Rough idle

Common Causes

• Faulty MAF sensor

• Dirty or clogged air filter

• Vacuum leaks

Glossary

MAF Sensor: Mass Air Flow Sensor, a device that measures the amount of air entering the engine.

ECM: Engine Control Module, the computer that controls engine functions.

Related Codes

• P0101

• P0102

Laymans terms

This code means that the car's computer is having trouble with the sensor that measures how much air is going into the engine. It's like when you can't tell how much air is in a balloon because the balloon is not working right.

Explanation

The Mass Air Flow (MAF) sensor measures the amount of air entering the engine, which is crucial for the engine control unit to balance and deliver the correct fuel mass to the engine. A P1140 code indicates a performance issue or range problem with this sensor.

Technical description

The P1140 code is triggered when the Engine Control Module (ECM) detects a problem with the Mass Air Flow (MAF) sensor circuit. This could be due to an incorrect signal range or performance issue, affecting the air-fuel ratio and engine performance.

Diagnosis steps

• Scan the vehicle for codes and freeze frame data

• Inspect the MAF sensor and wiring for damage

• Check the air filter and intake system for obstructions

Repair procedures

• Clean or replace the MAF sensor

• Replace the air filter

• Repair any vacuum leaks

Tools required

• OBD-II scanner

• Multimeter

• Screwdriver set

Estimated repair cost

$100 - $300

Difficulty level

Moderate

Commonly affected vehicles

• Nissan Altima

• Toyota Camry

• Honda Accord

Preventive measures

• Regularly replace the air filter

• Keep the MAF sensor clean

• Inspect for vacuum leaks periodically

Error code type

Sensor Issue

User experience recommendations

• Do not ignore the Check Engine Light

• Have the issue diagnosed and repaired promptly

Warranty information

Check with your vehicle manufacturer for any applicable warranties on the MAF sensor.

Historical data

The P1140 code has been associated with MAF sensor issues in vehicles since the introduction of OBD-II systems in the mid-1990s.

Urgency level

Moderate – Addressing this issue promptly can prevent further engine performance problems.

Legal and safety notice

Driving with a malfunctioning MAF sensor can lead to increased emissions and may not comply with local emissions regulations.

Testing conditions

• Engine at operating temperature

• Vehicle in park or neutral

Component location

The MAF sensor is typically located between the air filter box and the throttle body in the engine bay.

FAQs

Q: Can I drive with a P1140 code?
A: While you may be able to drive for a short period, it's best to have the issue diagnosed and repaired to avoid further damage.

Q: How often should I replace my air filter?
A: It's generally recommended to replace the air filter every 12,000 to 15,000 miles, but check your vehicle's manual for specifics.

Last updated: Jun 9, 2026 • Source: internal database

Diagnose Your Check Engine Light