AutoCodes – Generic – P1149

P1149 Code - Air/Fuel Ratio Sensor 1 Circuit Range/Performance

Quick Answer

The Air/Fuel Ratio (A/F) sensor 1 is installed in the exhaust system and detects oxygen content in the exhaust gas. Common causes include Faulty Air/Fuel Ratio Sensor 1, Air/Fuel Ratio Sensor 1 harness is open or shorted, Air/Fuel Ratio Sensor 1 circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1149 indicates Air/Fuel Ratio Sensor 1 Circuit Range/Performance.
Common causes: Common causes include Faulty Air/Fuel Ratio Sensor 1, Air/Fuel Ratio Sensor 1 harness is open or shorted, Air/Fuel Ratio Sensor 1 circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 8,377

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 02, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1149 Description

The Air/Fuel Ratio (A/F) sensor 1 is installed in the exhaust system and detects oxygen content in the exhaust gas. The A/F sensor transmits output voltage to the Engine Control Module (ECM)/Powertrain Control Module (PCM). A heater for the sensor element is embedded in the A/F sensor (sensor 1). It is activated and heats the sensor to stabilize and speed the detection of oxygen content by controlling current flowing through the heater. An increase in the current levels off as the applied voltage to the element electrode reaches a certain range because the amount of oxygen which is led through the diffusion layer is limited. The current amperage is proportional to oxygen content in the exhaust gas, so the air/fuel ratio is detected by the measurement of the current amperage. The ECM/PCM compares a set target air/fuel ratio with the detected air/fuel ratio and controls the fuel injection timing.
If the A/F sensor (sensor 1) voltage is low, the air/fuel ratio is lean, and the ECM/PCM uses A/F feedback control to issue a Rich command. If the A/F sensor (sensor 1) voltage is high, the air/fuel ratio is rich, and the ECM/PCM uses A/F feedback control to issue a Lean command.
If the element is not activated or the ECM/PCM terminal voltage is a set value or less for at least a set time period when the power is drawn to the A/F sensor (sensor 1) heater, a malfunction is detected and a DTC is stored.

OBDII Code P1149 - Air/Fuel Ratio Sensor 1 Circuit Range/Performance - AutoCodes.com — P1149 Code - Air/Fuel Ratio Sensor 1 Circuit Range/Performance

What does this mean?

What are the Possible Causes of the DTC P1149?

Faulty Air/Fuel Ratio Sensor 1
Air/Fuel Ratio Sensor 1 harness is open or shorted
Air/Fuel Ratio Sensor 1 circuit poor electrical connection

How to Fix the DTC P1149?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1149 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P1149 code?

Need more information on how to fix the P1149 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1149 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P1149 Acura — Air/Fuel Ratio Sensor 1 Circuit Range/Performance
P1149 Audi — HO2S11 Implausible Control Value
P1149 Honda — Air/Fuel Ratio Sensor 1 Circuit Range/Performance
P1149 Volkswagen — HO2S11 Implausible Control Value

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1149 Code

1. What does the OBDII code P1149 mean?

P1149 indicates an issue with the Air/Fuel Ratio Sensor 1, where its circuit is operating outside the expected range or performance parameters.

2. What are the common symptoms of code P1149?

Symptoms may include a lit check engine light, reduced fuel efficiency, poor engine performance, rough idling, or hesitation during acceleration.

3. What causes the P1149 code to appear?

Common causes include a faulty air/fuel ratio sensor, damaged wiring or connectors, exhaust leaks, or an issue with the engine control module (ECM).

4. Can I drive with a P1149 code?

While the vehicle may still be operable, driving with this code can lead to reduced fuel efficiency and potential engine damage if not addressed promptly.

5. How is code P1149 diagnosed?

A mechanic will use a scan tool to verify the code, inspect the air/fuel ratio sensor, check for wiring issues, and test the ECM for proper function.

6. What repairs are needed to fix a P1149 code?

Repairs may include replacing the air/fuel ratio sensor, repairing damaged wiring or connectors, fixing exhaust leaks, or reprogramming or replacing the ECM.

7. How much does it cost to fix a P1149 code?

Repair costs vary but typically range from $200 to $500, depending on whether the air/fuel ratio sensor needs replacement or if additional repairs are required.

8. Can I reset the P1149 code without fixing the issue?

Clearing the code without addressing the underlying problem will only result in the code returning, and it may lead to further vehicle issues.

9. Is the P1149 code specific to certain vehicles?

Yes, the P1149 code is commonly associated with Honda and Acura vehicles but may appear in other makes with similar diagnostics.

10. How can I prevent the P1149 code from recurring?

Regular maintenance, ensuring proper sensor installation, and promptly addressing exhaust and wiring issues can help prevent this code from reappearing.