AutoCodes – Mazda – P0158 Mazda

P0158 Mazda Code - HO2S LR Circuit High Input

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: P0158 Mazda indicates HO2S LR Circuit High Input.
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 7,087

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 P0158 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 P0158 Mazda - HO2S LR Circuit High Input - AutoCodes.com — P0158 Mazda Code - HO2S LR Circuit High Input

What does this mean?

What are the Possible Causes of the DTC P0158 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
Exhaust gas leaks

How to Fix the DTC P0158 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 Rear Heated Oxygen Sensor Bank 2 usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0158 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.

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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 P0158 Mazda Code

1. What are the common symptoms of OBDII code P0158 in a Mazda?

- Common symptoms include poor fuel economy, rough idling, engine misfires, and the illumination of the Check Engine Light.

2. What does the OBDII code P0158 "HO2S LR Circuit High Input" mean for a Mazda?

- This code indicates that the oxygen sensor in the left bank of the engine is providing a high voltage signal to the engine control module.

3. What are the typical causes of OBDII code P0158 in a Mazda?

- The most common causes of this code are a faulty oxygen sensor, wiring issues in the oxygen sensor circuit, exhaust leaks, or a malfunctioning engine control module.

4. How can I diagnose the OBDII code P0158 in my Mazda?

- Diagnosis involves checking the oxygen sensor's wiring and connections, testing the sensor's voltage output, inspecting for exhaust leaks, and scanning the engine control module for related trouble codes.

5. Can I drive my Mazda with OBDII code P0158 without causing further damage?

- It's not recommended to drive your Mazda with this code present, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter over time.

6. How can I repair OBDII code P0158 in my Mazda?

- Repair options include replacing the oxygen sensor, repairing any damaged wiring or connectors, fixing exhaust leaks, or reprogramming the engine control module if necessary.

7. Will resetting the Check Engine Light resolve OBDII code P0158 in my Mazda?

- Resetting the Check Engine Light may temporarily turn it off, but it will not fix the underlying issue causing the code. Proper diagnosis and repair are necessary to resolve the problem.

8. Are there any DIY tips for addressing OBDII code P0158 in a Mazda?

- DIY enthusiasts can start by inspecting the oxygen sensor connections, checking for visible wiring damage, and ensuring there are no exhaust leaks before seeking professional help if needed.

9. How much does it typically cost to repair OBDII code P0158 in a Mazda?

- The cost of repairing this code can vary depending on the root cause, but it generally ranges from $100 to $300 for parts and labor, excluding any potential additional repairs.

10. Is it necessary to have OBDII code P0158 cleared by a mechanic after repairs are completed on my Mazda?

- Yes, it is recommended to have a mechanic clear the code using a diagnostic scan tool after repairs to ensure the issue has been successfully resolved.