For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provide an overview of each diagnostic category.

### DTC Descriptors

DTC P0133: HO2S Slow Response Bank 1 Sensor 1
DTC P0153: HO2S Slow Response Bank 2 Sensor 1

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
HO2S Bank 1 Sensor 1 Signal | P0131 | P0130, P0134 | P0132 | P0130, P0133
HO2S Bank 1 Sensor 2 Signal | P0137 | P0140 | P0138 | P0139
HO2S Bank 2 Sensor 1 Signal | P0151 | P0150, P0154 | P0152 | P0150, P0153
HO2S Bank 2 Sensor 2 Signal | P0157 | P0160 | P0158 | P0159
Low Reference | -- | P0130, P0150, | P0134, P0140, P0154, P0160 | --

### Circuit Description

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio. If the ECM detects that the HO2S signal voltage is low, this DTC sets.

### Conditions for Running the DTC

• | Before the ECM can report DTC P0133 or P0153 failed, DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0336, and P0338 must run and pass.

• | DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0053, P0059, P0130, P0131, P0132, P0135, P0150, P0151, P0152, P0155, P0443, P0458, P0459, P2096, P2097, P2098, P2099, P2231, P2234, P2297, and P2298 are not set.

• | The HO2S is at operating temperature.

• | The HO2S is between 0.94-1.06 lambda.

• | The engine speed is between 1,480-2,040 RPM.

• | The volumetric efficiency is between 16.5-38.3 percent.

• | The change in volumetric efficiency is less than 3 percent.

• | The evaporative emission (EVAP) purge is not active, or the ECM determines the EVAP hydrocarbon (HC) concentration is less than a predetermined amount when EVAP purge is active.

• | The long term fuel trim correction is active.

• | DTCs P0133 and P0153 run continuously once the above conditions are met for 10 minutes.

### Conditions for Setting the DTC

The ECM has determined that the dynamic value of the affected HO2S is less than a predetermined threshold for greater than 4 seconds.

### Action Taken when the DTCs Set

DTCs P0133 and P0153 are Type B DTCs.

### Conditions for Clearing the MIL/DTCs

DTCs P0133 and P0153 are Type B DTCs.

### Diagnostic Aids

• | The front wide band sensors do not toggle or switch like a switching HO2S. The front HO2S signals will be relatively stable for an idling engine.

• | A loose HO2S can cause this DTC to set.

• | The following table illustrates the typical voltages for the HO2S circuits:

#### HO2S Voltages

HO2S Circuit | Voltage
--- | ---

• | Ignition ON, Engine OFF

• | HO2S Disconnected

Heater Control | 4.6-5.0 V
Heater Supply Voltage | B+
Reference Voltage | 2.6-3.1 V
Low Reference | 2.2-2.7 V
Pump Current | 2.5-3.0 V
Input Pump Current | 2.5-3.0 V

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Verify that other DTCs are not set.

⇒ | If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

2. Engine running at normal operating temperature, verify the scan tool Loop Status Bn. 1 Sen. 1 and Loop Status Bn. 2 Sen. 1 parameters display Closed Loop.
3. Operate the vehicle within the conditions for running the DTC. DTCs P0133 and P0153 should not set.
4. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

### Circuit/System Testing

1. Verify that none of the following conditions exist:

• | Lean fuel injectors--Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2

• | Water intrusion in the HO2S harness connector

• | HO2S wiring harness damage

• | Incorrect RTV sealant

• | Low fuel system pressure--Refer to Fuel System Diagnosis

• | Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis

• | Fuel saturation of the evaporative emission (EVAP) canister

• | Exhaust leaks near the HO2S

• | Engine vacuum leaks

• | Engine oil consumption

• | Engine coolant consumption

⇒ | If you find any of the above conditions, repair as necessary.

2. If all conditions test normal, replace the appropriate HO2S.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 1

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 2

• | Control Module References for engine control module replacement, setup, and programming