Engine-Codes - Ford - P1138 1998 FORD F150

P1138 1998 FORD F150 - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich

Repair Importance Level: 3/3
Repair Difficulty Level: 2/3  What is this?
Table of contents

P1138 1998 FORD F150 Possible Causes

  • Exhaust gas leaks
  • Faulty Heated Oxygen Sensor 2 (HO2S2) (Downstream) Bank 1
  • Heated Oxygen Sensor 2 Bank 1 harness is open or shorted
  • Heated Oxygen Sensor 2 Bank 1 circuit poor electrical connection
  • Inappropriate fuel pressure
  • Faulty fuel injectors

How is the P1138 1998 FORD F150 code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

What is the cost to diagnose the P1138 1998 FORD F150 code

Labor: 1.0

The cost to diagnose the P1138 1998 FORD F150 code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
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Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P1138 1998 FORD F150 Meaning

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 P1138 code will set when the PCM detects that the HO2S2 signal is above the voltage of range for an extended period.

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