AutoCodes – Mazda – P0159 Mazda

P0159 Mazda Code - HO2S LR Circuit Problem

Quick Answer

The heated oxygen sensor 2 (HO2S), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Rear Heated Oxygen Sensor Bank 2, Rear Heated Oxygen Sensor Bank 2 harness is open or shorted, Rear Heated Oxygen Sensor Bank 2 circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0159 Mazda indicates HO2S LR Circuit Problem.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 2, Rear Heated Oxygen Sensor Bank 2 harness is open or shorted, Rear Heated Oxygen Sensor Bank 2 circuit poor electrical connection.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 4,400

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0159 Mazda Description

The heated oxygen sensor 2 (HO2S), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Engine Control Module (ECM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.

OBDII Code P0159 Mazda - HO2S LR Circuit Problem - AutoCodes.com — P0159 Mazda Code - HO2S LR Circuit Problem

What does this mean?

What are the Possible Causes of the DTC P0159 Mazda?

Faulty Rear Heated Oxygen Sensor Bank 2
Rear Heated Oxygen Sensor Bank 2 harness is open or shorted
Rear Heated Oxygen Sensor Bank 2 circuit poor electrical connection
Inappropriate fuel pressure
Faulty fuel injectors
Intake air leaks may be faulty
Exhaust gas leaks

How to Fix the DTC P0159 Mazda?

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 does this mean?

Code Tech Notes

Replacing the O2 Sensor 2 usually takes care of the problem

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0159 Mazda 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 P0159 Mazda code?

Need more information on how to fix the P0159 Mazda code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0159 Mazda code diagnosed by a professional: Find a repair shop in your area

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 P0159 Mazda Code

1. What are the common symptoms of OBDII code P0159 in a Mazda?

- Common symptoms include poor fuel economy, rough idling, hesitation during acceleration, and an illuminated Check Engine Light.

2. What does the OBDII code P0159 indicate in a Mazda?

- OBDII code P0159 specifically points to a problem with the Heated Oxygen Sensor (HO2S) circuit on the left side or bank 2 of the engine.

3. What are the potential causes of the HO2S LR circuit problem in a Mazda?

- The causes can range from a faulty oxygen sensor, damaged wiring or connectors, to issues with the engine's computer (ECU) or other related components.

4. How can I diagnose the HO2S LR circuit problem in my Mazda?

- Diagnosing the issue involves using an OBDII scanner to retrieve the fault code, inspecting the wiring and connectors for damage, and testing the oxygen sensor's functionality.

5. Can I drive my Mazda with OBDII code P0159?

- It is generally not recommended to drive your Mazda with an unresolved OBDII code P0159, as it can lead to decreased fuel efficiency and potential damage to the engine over time.

6. How can I fix the HO2S LR circuit problem in my Mazda?

- Repairing the issue may involve replacing the faulty oxygen sensor, repairing damaged wiring or connectors, resetting the ECU, and clearing the fault code with an OBDII scanner.

7. Is it possible to reset the Check Engine Light caused by code P0159 in a Mazda?

- Yes, the Check Engine Light can be reset by fixing the underlying issue triggering the code P0159 and using an OBDII scanner to clear the fault code.

8. Can a DIY enthusiast repair the OBDII code P0159 in a Mazda?

- Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to address the HO2S LR circuit problem by following repair guides and diagnostic procedures.

9. How much does it cost to repair OBDII code P0159 in a Mazda?

- Repair costs can vary depending on the root cause of the issue, but expenses may include the price of a new oxygen sensor, replacement wiring, labor costs if taken to a mechanic, and diagnostic fees.

10. Will fixing the HO2S LR circuit problem improve my Mazda's performance?

- Resolving the OBDII code P0159 can lead to improved engine performance, better fuel efficiency, smoother idling, and a more reliable driving experience in your Mazda.