AutoCodes – Toyota – P2238 2005 Toyota Prius

P2238 2005 Toyota Prius Code - Oxygen A/F Sensor Reference Ground Circuit High Bank 1 Sensor 1

Quick Answer

The Air-Fuel ratio (A/F) sensor provides output voltage approximately equal to the existing air-fuel ratio. Common causes include Faulty EFI Relay, Faulty Air/Fuel Sensor Bank 1, Air/Fuel Sensor Bank 1 harness is open or shorted. 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: P2238 2005 Toyota Prius indicates Oxygen A/F Sensor Reference Ground Circuit High Bank 1 Sensor 1.
Common causes: Common causes include Faulty EFI Relay, Faulty Air/Fuel Sensor Bank 1, Air/Fuel Sensor Bank 1 harness is open or shorted.
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 4,570

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
Cost to Diagnose
FAQs
Comments
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Code P2238 2005 Toyota Prius Description

The Air-Fuel ratio (A/F) sensor provides output voltage approximately equal to the existing air-fuel ratio.
The A/F sensor output voltage is used to provide feedback for the Engine Control Module (ECM) to control the air-fuel ratio.
With the A/F sensor output, the ECM can determine deviation from the stoichiometric air-fuel ratio and control proper injection time. If the A/F sensor is malfunctioning, the ECM is unable to accurately control air-fuel ratio.
The A/F sensor is equipped with a heater which heats the zirconia element. The heater is also controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), current flows to the heater which heats the sensor to facilitate detection of accurate oxygen concentration.
The A/F sensor is a planar type. Compared to a conventional type, the sensor and heater portions are narrower. Because the heat of the heater is conducted through the alumina to zirconia (of the sensor portion), sensor activation is accelerated.

The code is output when there is an open or short in the A/F sensor circuit, or if A/F sensor output drops. To detect these problems, the voltage of the A/F sensor is monitored when turning the ignition switch to the ON position, and the admittance (admittance is an electrical term that indicates the ease of flow of current) is checked while driving. If the voltage of the A/F sensor is between 0.6 V and 4.5 V, it is considered normal. If the voltage is outside of the specified range, or the admittance is less than the standard value, the ECM will determine that there is a malfunction in the A/F sensor. If the same malfunction is detected in the next driving cycle, the MIL is illuminated and a DTC is set.

OBDII Code P2238 2005 Toyota Prius - Oxygen A/F Sensor Reference Ground Circuit High Bank 1 Sensor 1 - AutoCodes.com — P2238 2005 Toyota Prius Code - Oxygen A/F Sensor Reference Ground Circuit High Bank 1 Sensor 1

What does this mean?

What are the Possible Causes of the DTC P2238 2005 Toyota Prius?

Faulty EFI Relay
Faulty Air/Fuel Sensor Bank 1
Air/Fuel Sensor Bank 1 harness is open or shorted
Air/Fuel Sensor Bank 1 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P2238 2005 Toyota Prius?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P2238 2005 Toyota Prius 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 P2238 2005 Toyota Prius code?

Need more information on how to fix the P2238 2005 Toyota Prius code? Get Access to Factory Service Manuals

Need Help with the Code?

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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 P2238 2005 Toyota Prius Code

1. What are the common symptoms of OBDII code P2238 in a 2005 Toyota Prius?

The common symptoms of code P2238 include poor fuel efficiency, rough idling, and a possible decrease in engine performance.

2. What does the OBDII code P2238 in a 2005 Toyota Prius indicate?

Code P2238 indicates a high voltage in the reference circuit of the Bank 1 Sensor 1 oxygen A/F sensor in the Toyota Prius.

3. What are the possible causes of OBDII code P2238 in a 2005 Toyota Prius?

Possible causes of code P2238 include a faulty oxygen A/F sensor, damaged wiring or connectors in the sensor circuit, or issues with the engine control module (ECM).

4. How can I diagnose the OBDII code P2238 in my 2005 Toyota Prius?

To diagnose code P2238, you can use an OBDII scanner to retrieve the code and inspect the wiring, connectors, and the oxygen A/F sensor itself for any visible damage or issues.

5. Can I continue driving my 2005 Toyota Prius with OBDII code P2238?

It is not recommended to drive your Prius with code P2238 as it can lead to decreased fuel efficiency and potential engine performance issues. It is advisable to address the problem promptly.

6. How can I repair OBDII code P2238 in my 2005 Toyota Prius?

To repair code P2238, you may need to replace the Bank 1 Sensor 1 oxygen A/F sensor, repair any damaged wiring or connectors in the circuit, or reprogram the engine control module (ECM).

7. Is it possible to reset OBDII code P2238 in a 2005 Toyota Prius without fixing the underlying issue?

While you can clear the code temporarily, it is crucial to address the underlying problem causing code P2238 to prevent it from reoccurring and potentially causing further issues.

8. Is OBDII code P2238 a common issue in 2005 Toyota Prius vehicles?

Code P2238 can be a common issue in some 2005 Toyota Prius vehicles due to factors like age, mileage, and wear on components like the oxygen A/F sensor and wiring.

9. Can a DIY enthusiast fix OBDII code P2238 in a 2005 Toyota Prius?

Depending on your skill level and access to tools, a DIY enthusiast may be able to fix code P2238 by replacing the oxygen A/F sensor or repairing wiring issues. However, professional help may be needed for more complex repairs.

10. How can I prevent OBDII code P2238 from occurring in my 2005 Toyota Prius in the future?

Regular maintenance, such as checking and replacing oxygen sensors as recommended, inspecting wiring for damage, and addressing any engine performance issues promptly, can help prevent code P2238 from occurring in the future.