AutoCodes – Generic – P1148

P1148 Code - Closed Loop Control Function Bank 1

Quick Answer

The Engine Control Module (ECM) performs ON/OFF duty control of the Air Fuel Ratio (A/F)/Heated Oxygen Sensor 1 heater corresponding to the engine operating condition to keep the temperature of Air Fuel Ratio (A/F)/Heated Oxygen Sensor 1 element at the specified range. Common causes include Faulty Heated Oxygen Sensor 1 Bank 1, Heated Oxygen Sensor 1 Bank 1 circuit is open or shorted, Heated Oxygen Sensor 1 Bank 1 circuit 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: P1148 indicates Closed Loop Control Function Bank 1.
Common causes: Common causes include Faulty Heated Oxygen Sensor 1 Bank 1, Heated Oxygen Sensor 1 Bank 1 circuit is open or shorted, Heated Oxygen Sensor 1 Bank 1 circuit 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 76,721

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 Jul 21, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1148 Description

The Engine Control Module (ECM) performs ON/OFF duty control of the Air Fuel Ratio (A/F)/Heated Oxygen Sensor 1 heater corresponding to the engine operating condition to keep the temperature of Air Fuel Ratio (A/F)/Heated Oxygen Sensor 1 element at the specified range. The Diagnostic Trouble Code (DTC) will be set when the closed loop control function for bank 1 does not operate even when the vehicle is driving in the specified condition or the closed loop control function for bank 2 does not operate even when the vehicle is driving in the specified condition.

OBDII Code P1148 - Closed Loop Control Function Bank 1 - AutoCodes.com — P1148 Code - Closed Loop Control Function Bank 1

What does this mean?

What are the Possible Causes of the DTC P1148?

Faulty Heated Oxygen Sensor 1 Bank 1
Heated Oxygen Sensor 1 Bank 1 circuit is open or shorted
Heated Oxygen Sensor 1 Bank 1 circuit electrical connection

How to Fix the DTC P1148?

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 P1148 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

P1148 Audi — HO2S21 System Too Rich
P1148 Chrysler — Fuel Rail Pressure Malfunction Pressure Drop In Over-run
P1148 Dodge — Fuel Rail Pressure Malfunction Pressure Drop In Over-run
P1148 Ford — Closed Loop Control Malfunction
P1148 Infiniti — Closed Loop Control Function Bank 1
P1148 Jeep — Fuel Rail Pressure Malfunction Pressure Drop In Over-run
P1148 Lincoln — Closed Loop Control Malfunction
P1148 Mercury — Closed Loop Control Malfunction
P1148 Nissan — Closed Loop Control Function Bank 1
P1148 Volkswagen — HO2S21 System Too Rich

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.