AutoCodes – Generic – P2A01

P2A01 Code - O2 Sensor Circuit Range/Performance Bank 1 Sensor 2

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 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection. 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: P2A01 indicates O2 Sensor Circuit Range/Performance Bank 1 Sensor 2.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection.
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.

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Code Popularity 51,695

How popular is this code, among other codes? Medium

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Feb 16, 2019

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P2A01 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 P2A01 - O2 Sensor Circuit Range/Performance Bank 1 Sensor 2 - AutoCodes.com — P2A01 Code - O2 Sensor Circuit Range/Performance Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P2A01?

Faulty Rear Heated Oxygen Sensor Bank 1
Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
Inappropriate fuel pressure
Faulty fuel injectors
Intake air leaks may be faulty
Exhaust gas leaks

How to Fix the DTC P2A01?

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 O2 Sensor bank 1 usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P2A01 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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Information for Specific Makes

P2A01 Buick — O2 Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 Cadillac — O2 Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 Chevrolet — O2 Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 Dodge — O2 Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 Ford — Oxygen Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 GMC — O2 Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 Hyundai — O2 Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 KIA — O2 Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 Lincoln — Oxygen Sensor Circuit Range/Performance Bank 1 Sensor 2
P2A01 Mercury — Oxygen Sensor Circuit Range/Performance Bank 1 Sensor 2

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.