AutoCodes – KIA – P0155 KIA

P0155 KIA Code - HO2S21 Heater Circuit

Quick Answer

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground. 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: P0155 KIA indicates HO2S21 Heater Circuit.
Common causes: Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground.
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 6,791

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 Mar 23, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0155 KIA Description

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. The faster the heated oxygen sensor reaches that temperature the faster the sensor will start sending an accurate signal to the Engine Control Module (ECM). In order to achieve the require temperature, a heater element is included inside the heated oxygen sensor. The ECM controls the heated oxygen sensor heater element based on signals from the engine coolant temperature and engine load. The ECM controls the heater element circuit by allowing current flow to ground. The ECM monitors the voltage signal received through the heater element circuit and determines the state of the circuit by comparing the voltage detected with the factory specifications.

OBDII Code P0155 KIA - HO2S21 Heater Circuit - AutoCodes.com — P0155 KIA Code - HO2S21 Heater Circuit

What does this mean?

What are the Possible Causes of the DTC P0155 KIA?

Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0155 KIA?

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

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The Engine Control Module (ECM) monitors how long it take the sensor to warm up and start sending an adequate signal. The code means the the sensor is taking too long to warm up. Replacing the Front Heated Oxygen Sensor (H2OS) Bank 2 usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0155 KIA 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 P0155 KIA Code

1. What does the OBDII code P0155 mean on a Kia?

P0155 indicates a problem with the heater circuit of the oxygen sensor (HO2S21) located in Bank 2, Sensor 1, which is upstream of the catalytic converter on the second bank of cylinders.

2. What are the common symptoms of P0155 on a Kia?

Symptoms may include an illuminated Check Engine Light, decreased fuel efficiency, rough idling, or delayed engine warm-up.

3. What causes the P0155 code to appear on a Kia?

Common causes include a faulty oxygen sensor, damaged wiring or connectors, a blown fuse, or issues with the engine control module (ECM).

4. Can I drive my Kia with a P0155 code?

While the car may still be drivable, continued driving with this code can lead to decreased fuel efficiency and potential damage to the catalytic converter if left unresolved.

5. How do I diagnose the P0155 code on a Kia?

Start by inspecting the wiring and connectors for damage or corrosion, checking the oxygen sensor's resistance, and testing the heater circuit with a multimeter.

6. How do I fix the P0155 code on my Kia?

Repairs may involve replacing the faulty oxygen sensor, repairing damaged wiring or connectors, or replacing a blown fuse. In rare cases, the ECM may need reprogramming or replacement.

7. How much does it cost to fix a P0155 code on a Kia?

Replacing an oxygen sensor typically costs between $150 and $300, including parts and labor. Wiring repairs or ECM replacement may vary in cost.

8. Can a bad oxygen sensor cause other problems on my Kia?

Yes, a faulty oxygen sensor can affect engine performance, increase emissions, and cause damage to the catalytic converter over time.

9. What tools do I need to troubleshoot the P0155 code on a Kia?

You may need an OBDII scanner, a multimeter, a socket set for removing the oxygen sensor, and potentially a wiring diagram for your Kia model.

10. How can I prevent the P0155 code from occurring on my Kia?

Regular vehicle maintenance, including inspecting and replacing oxygen sensors as recommended, and ensuring wiring and connectors are in good condition, can help prevent this code.