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 provides an overview of each diagnostic category. |
DTC Descriptors
DTC P2196: HO2S Signal Biased Rich Sensor 1Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
HO2S 1 Signal | P0131 | P2243 | P0132 | -- |
HO2S 1 Low Reference | P0131 | P0135 | P0132 | -- |
HO2S 2 Signal | P0137 | P0140 | P0137, P2096 | -- |
HO2S 2 Low Reference | -- | P0140 | -- | -- |
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 greater 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.
Conditions for Running the DTC
| • | Before the ECM can report DTC P2196 failed, DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0053, P0101, P0130, P0131, P0132, P0133, P0135, P0137, P0138, P0140, P0141, P167A, P2231, P2237, P2243, P2251, P2270, P2271, P2297 and P2626 must run and pass. |
| • | The front and rear HO2S are at operating temperature. |
| • | The HO2S 2 voltage signal is less than 150 mV. |
| • | The HO2S 1 is greater than 0.940 lambda. |
| • | The Loop Status of the HO2S 1 and HO2S 2 is Closed Loop. |
| • | DTC P2196 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
Conditions 1
| • | The ECM detects that the front HO2S is operating too rich while the rear HO2S is operating too lean and the ECM detects that the fuel trim is at minimum control. |
| OR |
| • | The rear fuel trim, long and short term, is less than a threshold. |
| • | This DTC sets after the air flow coming into the engine accumulates to greater than 200 grams and the above conditions are met for greater than 4 seconds, or for a cumulative of 50 seconds. |
Conditions 2
| • | The ECM detects that the rear HO2S is operating too lean while the ECM is commanding a rich a rich air/fuel mixture, desired lambda less than 0.960. |
| • | This DTC sets after the air flow coming into the engine accumulates to greater than 800 grams and the above condition is met for greater than 4 seconds, or for a cumulative of 50 seconds. |
Action Taken when the DTC Sets
DTC P2196 is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P2196 is a Type B DTC.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Diagnostic Aids
The following table illustrates the ECM connector locations:
ECM Connector Location | |
|---|---|
X2 | X1 |
Front of Vehicle | |
Circuit/System Verification
- Ignition ON, observe the scan tool DTC information. Verify DTCs P0137, P0138, or P0140 are not also set.
- Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
| ⇒ | If any of the above DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis. |
Caution: Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.
Important: The rear heated oxygen sensor (HO2S) must be in closed loop for this diagnostic to run. A road load condition is necessary to obtain closed loop.
Circuit/System Testing
- Verify that none of the following conditions exist:
- Ignition OFF, disconnect the harness connector at the HO2S 2.
- Ignition ON, verify the scan tool HO2S 2 voltage parameter is between 350-550 mV.
- Connect the harness connector at the HO2S 2.
- Engine idling, raise the engine speed above 1,200 RPM for 30 seconds. Verify the scan tool HO2S 2 voltage parameter is less than 1,000 mV.
- Engine idling, move the HO2S 1 and HO2S 2 harnesses between the HO2S harness connector and the ECM. Observe the scan tool HO2S 1 lambda parameter, and the HO2S 2 voltage parameter. Verify neither parameter changes abruptly.
- If all circuits/connections test normal, replace the HO2S 1.
| • | Inspect the HO2S 1 and HO2S 2 for being secure |
| • | Damaged wiring between either HO2S and the ECM |
| • | Leaking fuel injectors--Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 |
| • | High fuel system pressure--Refer to Fuel System Diagnosis |
| • | Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis |
| • | Contaminated HO2S-Silicon |
| ⇒ | If you find any of the above conditions, repair as necessary. |
| ⇒ | If greater than the specified range, test the HO2S 2 high signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If greater than the specified range, replace the HO2S 2. |
| ⇒ | If the parameter changes abruptly, repair the harness/connections as necessary. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
