AutoCodes – Generic – P1172

P1172 Code - Rear A/F Sensor Bank 1 Sensor 1 Circuit Out Of Range High

Quick Answer

The Air/Fuel Ratio (A/F) sensor 1 is installed in the exhaust system and detects oxygen content in the exhaust gas. Common causes include Faulty Air/Fuel Ratio Bank 1 Sensor 1, Air/Fuel Ratio Bank 1 Sensor 1 harness is open or shorted, Air/Fuel Ratio Bank 1 Sensor 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: P1172 indicates Rear A/F Sensor Bank 1 Sensor 1 Circuit Out Of Range High.
Common causes: Common causes include Faulty Air/Fuel Ratio Bank 1 Sensor 1, Air/Fuel Ratio Bank 1 Sensor 1 harness is open or shorted, Air/Fuel Ratio Bank 1 Sensor 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 37,968

How popular is this code, among other codes? Low

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 May 16, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1172 Description

The Air/Fuel Ratio (A/F) sensor 1 is installed in the exhaust system and detects oxygen content in the exhaust gas. The A/F sensor transmits output voltage to the Engine Control Module (ECM). A heater for the sensor element is embedded in the A/F sensor (sensor 1). It is activated and heats the sensor to stabilize and speed the detection of oxygen content by controlling current flowing through the heater. An increase in the current levels off as the applied voltage to the element electrode reaches a certain range because the amount of oxygen which is led through the diffusion layer is limited. The current amperage is proportional to oxygen content in the exhaust gas, so the air/fuel ratio is detected by the measurement of the current amperage. The ECM compares a set target air/fuel ratio with the detected air/fuel ratio and controls the fuel injection timing.
If the A/F sensor (sensor 1) voltage is low, the air/fuel ratio is lean, and the ECM uses A/F feedback control to issue a Rich command. If the A/F sensor (sensor 1) voltage is high, the air/fuel ratio is rich, and the ECM uses A/F feedback control to issue a Lean command.

OBDII Code P1172 - Rear A/F Sensor Bank 1 Sensor 1 Circuit Out Of Range High - AutoCodes.com — P1172 Code - Rear A/F Sensor Bank 1 Sensor 1 Circuit Out Of Range High

What does this mean?

What are the Possible Causes of the DTC P1172?

Faulty Air/Fuel Ratio Bank 1 Sensor 1
Air/Fuel Ratio Bank 1 Sensor 1 harness is open or shorted
Air/Fuel Ratio Bank 1 Sensor 1 circuit poor electrical connection

How to Fix the DTC P1172?

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 P1172 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

P1172 Acura — Air Fuel Ratio Sensor Circuit Out of Range High
P1172 Audi — Throttle Actuation Potentiometer Signal 2 Signal Too Low
P1172 BMW — Ambient Pressure Sensor Rationality Check
P1172 Chevrolet — Fuel Pump Insufficient Flow
P1172 Ford — Rotor Control Fault
P1172 GMC — Fuel Pump Insufficient Flow
P1172 Honda — Air Fuel Ratio Sensor Circuit Out of Range High
P1172 Hyundai — Electronic Throttle System Improper Motor Current
P1172 Land Rover — LH Bank Lambda Control Adaption Over Time Too Small
P1172 MINI — Ambient Pressure Sensor Rationality Check
P1172 Suzuki — Lambda Controller Limit Malfunction Bank 1 Too Lean
P1172 Volkswagen — Throttle Actuation Potentiometer Signal 2 Signal Too Low
P1172 Volvo — Long Term Fuel Trim

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.