• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Heater Control | P0031 | P0030, P0135 | P0032 | -- |
Heater Supply Voltage | P0013, P0023, P0031, P0458, P2088, P2092 | P0030, P0135 | -- | -- |
High Signal | P0131 | P0135, P2243, P2251 | P0132 | P0130 |
Low Signal | P0131 | P0131, P0135, P2251 | P0132 | P0130 |
Pump Current | P0131 | P2243, P2251, P2626 | P0132 | -- |
Input Pump Current | P0131 | P2237 | P0132 | -- |
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.
• | Before the ECM can report DTC P2237 failed, DTCs P0101, P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, and P0338 must run and pass. |
• | DTCs P0030, P0031, P0032, P0133, and P0135 are not set. |
• | The ignition 1 voltage is between 11-18 volts. |
• | The engine is operating in Closed Loop. |
• | The HO2S heater is at operating temperature. |
• | The ECM is commanding the lambda greater than 1.03 or less than 0.97. |
• | Greater than 200 grams of exhaust gas has passed. |
• | DTC P2237 runs continuously once the above conditions are met for approximately 8 seconds. |
• | Before the ECM can report DTC P2237 failed, DTCs P0101, P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, and P0338 must run and pass. |
• | The ignition 1 voltage is between 11-18 volts. |
• | The engine is operating in Closed Loop. |
• | The HO2S heater is at operating temperature. |
• | The ECM detects the internal HO2S signal voltage is between 1.49-1.51 volts. |
• | The ECM is commanding the lambda rich and then lean periodically with a change of greater than 2 percent. |
• | DTC P2237 runs continuously once the above conditions are met for greater than 1.5 seconds. |
• | Before the ECM can report DTC P2237 failed, DTCs P0101, P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, and P0338 must run and pass. |
• | The ignition 1 voltage is between 11-18 volts. |
• | The HO2S heater is at operating temperature. |
• | The ECM is commanding decel fuel cut-off for greater than 3 seconds. |
• | DTC P2237 runs continuously once the above conditions are met for greater than 2 seconds. |
• | The ECM detects the internal HO2S signal voltage is between 1.49-1.51 volts while the desired lambda is above or below a threshold. |
• | The above condition exists for greater than 4 seconds. |
• | The ECM stores the fuel trim control values after the above conditions are met. The ECM detects that the stored value and the current fuel trim control value deviates greater than 10 percent of the lambda value. |
• | The above condition exists for greater than 4 seconds. |
• | The ECM detects the internal HO2S signal voltage after a decel fuel shut-off is less than 1.7 volts. |
• | The above condition exists for greater than 4 seconds. |
DTC P2237 is a Type B DTC.
DTC P2237 is a Type B DTC.
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
The following table illustrates the ECM connector locations:
ECM Connector Location | |
---|---|
X2 | X1 |
Front of Vehicle |
• | The front wide band sensor does not toggle or switch like a switching HO2S. The front HO2S signal will be relatively stable for an idling engine. |
• | The following table illustrates the typical voltages for the HO2S circuits: |
HO2S Circuit | Voltage | ||||
---|---|---|---|---|---|
| |||||
Heater Control | 4.6-5.0 V | ||||
Heater Supply Voltage | B+ | ||||
High Signal | 2.6-3.1 V | ||||
Low Signal | 2.2-2.7 V | ||||
Pump Current | Less than 0.5 V | ||||
Input Pump Current | Less than 0.5 V |
⇒ | If less than the specified range, test the input pump current circuit for an open. If the circuit tests normal, replace the ECM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for engine control module replacement, setup, and programming |