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P1173 Mazda Code - HO2S-21 No Change Detected

Quick Answer

The P1173 code for Mazda vehicles indicates that the downstream oxygen sensor (HO2S-21) is not providing the expected feedback to the engine control module (ECM). Common causes include Faulty oxygen sensor, Wiring issues (short, open circuit), ECM malfunction. 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
P1173 Mazda indicates HO2S-21 No Change Detected.
Common causes
Common causes include Faulty oxygen sensor, Wiring issues (short, open circuit), ECM malfunction.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1173 Mazda Description

The P1173 code for Mazda vehicles indicates that the downstream oxygen sensor (HO2S-21) is not providing the expected feedback to the engine control module (ECM). This sensor is responsible for monitoring the oxygen levels in the exhaust gases after they pass through the catalytic converter. The ECM uses the data from this sensor to adjust the air-fuel mixture for optimal combustion efficiency.

OBDII Code P1173 Mazda - HO2S-21 No Change Detected
P1173 Mazda Code - HO2S-21 No Change Detected

Common Causes of P1173 Mazda

  1. Faulty oxygen sensor
  2. Wiring issues (short, open circuit)
  3. ECM malfunction
  4. Exhaust system leaks
  5. Contaminated sensor

Symptoms of P1173 Mazda

  1. Decreased fuel efficiency
  2. Engine hesitation or surging
  3. Rough idling or stalling
  4. Check Engine Light illuminated
  5. Poor overall engine performance

How to Fix P1173 Mazda

  1. Begin by performing a visual inspection of the oxygen sensor and its wiring. Look for any signs of damage or contamination.
  2. Use a multimeter to test the oxygen sensor's functionality. Compare the readings to the manufacturer's specifications.
  3. If the sensor is faulty, replace it with a new, OEM-quality sensor. Make sure to install it correctly and securely.
  4. Check the wiring for any damage or corrosion. Repair or replace any damaged wires as needed.
  5. Clear the error code from the ECM's memory and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P1173 Mazda

The cost of repairing a HO2S-21 No Change Detected issue can vary depending on the root cause of the problem. In general, the cost of a new oxygen sensor for a Mazda vehicle ranges from $50 to $200, depending on the model and sensor type. Labor costs at an auto repair shop can range from $100 to $300, depending on the shop's hourly rate and the complexity of the repair. Therefore, the total cost of repairing this issue could be anywhere from $150 to $500. It's important to get an accurate diagnosis from a qualified technician to determine the exact cause of the problem and the associated repair costs.

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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 P1173 Mazda Code

1. What does OBDII code P1173 mean for a Mazda?

P1173 indicates that the HO2S-21 (Heated Oxygen Sensor 2, Bank 1) is not detecting expected changes in the oxygen levels, suggesting a potential problem with the sensor or fuel system.

2. What are common symptoms of code P1173 in a Mazda?

Symptoms may include reduced engine performance, poor fuel economy, rough idling, hesitation during acceleration, and an illuminated check engine light.

3. What causes the P1173 code in a Mazda?

Common causes include a faulty HO2S-21 sensor, exhaust leaks, wiring issues, a malfunctioning fuel injector, or an incorrect air-fuel mixture.

4. Can a dirty or damaged oxygen sensor trigger code P1173?

Yes, a dirty, damaged, or failing oxygen sensor can cause the HO2S-21 to stop detecting changes in oxygen levels, leading to this code.

5. Is it safe to drive a Mazda with the P1173 code?

Driving with this code is not recommended as it can lead to poor engine performance and potential damage to the catalytic converter over time.

6. How do I fix the P1173 code on a Mazda?

Repairs may include replacing the oxygen sensor, fixing wiring or connector issues, repairing exhaust leaks, or addressing fuel system problems.

7. How can I diagnose the P1173 code in a Mazda?

Start by scanning for codes, inspecting the HO2S-21 sensor and its wiring, checking for exhaust leaks, and verifying the air-fuel mixture with a diagnostic tool.

8. Can a clogged fuel injector cause the P1173 code?

Yes, a clogged or malfunctioning fuel injector can disrupt the air-fuel mixture, leading to this code.

9. How much does it cost to repair a P1173 code in a Mazda?

Repair costs vary depending on the issue but typically range from $100 to $300 for parts and labor, with oxygen sensor replacement being the most common fix.

10. Will replacing the HO2S-21 sensor always fix the P1173 code?

Not always; while replacing the sensor often resolves the issue, underlying problems like wiring damage or fuel system faults may also need attention.

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