AutoCodes – Ford – P1157 Ford

P1157 Ford Code - Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean

Quick Answer

The Heated Oxygen Sensor 2 (HO2S2) (Downstream), after the three-way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Exhaust gas leaks, Faulty Heated Oxygen Sensor 2 (HO2S2) (Downstream) Bank 2, Heated Oxygen Sensor 2 Bank 2 harness is open or shorted. 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: P1157 Ford indicates Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean.
Common causes: Common causes include Exhaust gas leaks, Faulty Heated Oxygen Sensor 2 (HO2S2) (Downstream) Bank 2, Heated Oxygen Sensor 2 Bank 2 harness is open or shorted.
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 20,872

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 Jul 24, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1157 Ford Description

The Heated Oxygen Sensor 2 (HO2S2) (Downstream), after the 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 maintain near the ideal stoichiometric ratio. The HO2S2 output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Powertrain Control Module (PCM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S2 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 PCM interprets Lean when the HO2S2 voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The PCM interprets Rich when the HO2S2 voltage is above 0.45 V. The P1157 code will set when the PCM detects that the HO2S2 signal is below the voltage of range for an extended period.

OBDII Code P1157 Ford - Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean - AutoCodes.com — P1157 Ford Code - Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean

What does this mean?

What are the Possible Causes of the DTC P1157 Ford?

Exhaust gas leaks
Faulty Heated Oxygen Sensor 2 (HO2S2) (Downstream) Bank 2
Heated Oxygen Sensor 2 Bank 2 harness is open or shorted
Heated Oxygen Sensor 2 Bank 2 circuit poor electrical connection
Inappropriate fuel pressure
Faulty fuel injectors

How to Fix the DTC P1157 Ford?

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 P1157 Ford 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 Ford Models

P1157 1997 Ford F150 — Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean
P1157 1998 Ford F150 — Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean
P1157 1999 Ford F150 — Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean
P1157 2000 Ford F150 — Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean
P1157 2001 Ford F150 — Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean
P1157 2002 Ford F150 — Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean
P1157 2003 Ford F150 — Lack Of Heated Oxygen Sensor Switches Bank 2 Sensor 2 Indicates Lean

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.