AutoCodes – Generic – P0042

P0042 Code - HO2S Heater Control Circuit Bank 1 Sensor 3

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 1 Sensor 3, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 is open shorted to ground, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 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: P0042 indicates HO2S Heater Control Circuit Bank 1 Sensor 3.
Common causes: Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 is open shorted to ground, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 35,262

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
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0042 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 P0042 - HO2S Heater Control Circuit Bank 1 Sensor 3 - AutoCodes.com — P0042 Code - HO2S Heater Control Circuit Bank 1 Sensor 3

What does this mean?

What are the Possible Causes of the DTC P0042?

Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3
Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 is open shorted to ground
Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 poor electrical connection
Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 fuse
Faulty Engine Control Module (ECM)

How to Fix the DTC P0042?

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. Water getting inside the heated oxygen sensor connector can caused the heated oxygen sensor fuse to blow, which is a very common problem for this type codes. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0042 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 P0042 code?

Need more information on how to fix the P0042 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0042 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P0042 Audi — HO2S Heater Control Circuit Bank 1 Sensor 3
P0042 Volkswagen — HO2S Heater Control Circuit Bank 1 Sensor 3

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.