AutoCodes – Generic – P1159

P1159 Code - Air/Fuel Ratio Sensor 1 AFS+ Terminal Low Voltage

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: P1159 indicates Air/Fuel Ratio Sensor 1 AFS+ Terminal Low Voltage.
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 22,268

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 03, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1159 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). 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 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 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 uses A/F feedback control to issue a Lean command.

OBDII Code P1159 - Air/Fuel Ratio Sensor 1 AFS+ Terminal Low Voltage - AutoCodes.com — P1159 Code - Air/Fuel Ratio Sensor 1 AFS+ Terminal Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1159?

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 P1159?

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 P1159 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 P1159 code?

Need more information on how to fix the P1159 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1159 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P1159 Acura — Air/Fuel Ratio Sensor 1 AFS+ Terminal Low Voltage
P1159 BMW — Fuel Trim Adaptation Additive High Bank 1
P1159 Buick — HO2S Cross Counts Bank 2 Sensor 2
P1159 Cadillac — HO2S Cross Counts Bank 2 Sensor 2
P1159 Chevrolet — HO2S Cross Counts Bank 2 Sensor 2
P1159 Chrysler — Improper Start Attempt
P1159 Dodge — Improper Start Attempt
P1159 GMC — HO2S Cross Counts Bank 2 Sensor 2
P1159 Honda — Air/Fuel Ratio Sensor 1 AFS+ Terminal Low Voltage
P1159 Hyundai — Variable Intake Motor Malfunction
P1159 Jeep — Improper Start Attempt
P1159 KIA — Variable Intake Motor Malfunction
P1159 MINI — Fuel Trim Adaptation Additive High Bank 1

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 P1159 Code

What does the OBDII code P1159 mean?

P1159 indicates that the Air/Fuel Ratio Sensor 1 AFS+ terminal is detecting low voltage, which can impact proper fuel mixture adjustments.

What are the common symptoms of code P1159?

Symptoms may include reduced fuel efficiency, rough idling, poor acceleration, and the illumination of the check engine light.

What causes the P1159 code to appear?

Possible causes include a faulty air/fuel ratio sensor, damaged sensor wiring, loose electrical connections, or an issue with the engine control module (ECM).

Can I drive with a P1159 code?

Driving with a P1159 code is possible but not recommended, as it can lead to poor engine performance and potential long-term damage if not addressed.

How do I diagnose a P1159 code?

Diagnosis typically involves using a scan tool to check the sensor's voltage readings, inspecting the wiring and connectors, and testing the air/fuel ratio sensor for proper function.

What tools are needed to fix a P1159 code?

Common tools include an OBDII scanner, a multimeter for voltage testing, and basic hand tools to access and replace the sensor if needed.

How much does it cost to repair a P1159 code?

Repair costs vary but typically range from $200 to $400, depending on whether the air/fuel ratio sensor or other components need replacement.

Can a dirty air filter cause a P1159 code?

While unlikely, a severely clogged air filter can indirectly affect air/fuel mixture readings, so inspecting and replacing it if needed is a good preventive step.

Do I need to replace the air/fuel ratio sensor to fix a P1159 code?

Not always; first inspect the wiring and connectors for damage. If they are intact, testing or replacing the sensor may be necessary.

How can I prevent a P1159 code from occurring again?

Regular maintenance, such as inspecting wiring, ensuring proper sensor function, and keeping the engine in good condition, can help prevent this code from reoccurring.