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| • | 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 Voltage Supply | P0030 00 | P0030 00 | - | - |
Reference Voltage (Signal) | P2245 00 | P2246 00 | P2246 00 | P2A00 |
Heater Low Control | P0031 00 | P0030 00 | P0032 00 | - |
Pump Current Control | P2238 00 | P2237 00 | - | - |
Low Reference (Ground) | - | P2251 00 | - | - |
The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust stream more quickly and accurately 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 signal 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 signal voltage. The ECM monitors the voltage variation on the signal circuit and attempts to keep the voltage constant by increasing or decreasing the amount of current flow or reversing the direction of the current flow to the pumping cell. By measuring the direction and amount of current required to maintain the signal voltage.
| • | The ignition voltage is between 10.7-18.1 V. |
| • | The engine is running. |
| • | HO2S 1 voltage is between 1.48-1.52 V. |
| • | HO2S 1 heater is at operating temperature. |
| • | HO2S 1 Closed Loop is active. |
| • | The catalyst temperature is stable. |
| • | DTC P2237 runs continuously when the above conditions are met for 2 s. |
| • | The ignition voltage is between 10.7-18.1 V. |
| • | The engine is running. |
| • | DTCs P2238 runs continuously when the above conditions have been met for 1.5 s. |
| • | The ECM detects that the pumping current circuit is open. |
| • | DTC P2237 sets within 4 s when the above condition is met continuously, or within 50 s when the above condition is met cumulatively. |
| • | The ECM detects that the HO2S 2 voltage is less than 1.7 V during deceleration fuel cut-off. |
| • | DTC P2238 sets when the above condition has been met for 3 s. |
DTCs P2237 00 and P2238 00 are Type B DTCs.
DTCs P2237 00 and P2238 00 are Type B DTCs.
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
| • | B52 Heated Oxygen Sensor Terminal A and the K20 Engine Control Module terminal 55 |
| • | B52 Heated Oxygen Sensor Terminal B and the K20 Engine Control Module terminal 54 |
| • | B52 Heated Oxygen Sensor Terminal E and the K20 Engine Control Module terminal 57 |
| • | B52 Heated Oxygen Sensor Terminal F and the K20 Engine Control Module terminal 56 |
| ⇒ | If greater than the specified range, test the circuit for an open/high resistance |
| ⇒ | If less than the specified value, repair the short to ground as necessary. |
| ⇒ | If less than the specified value, repair as necessary. |
| ⇒ | If greater than the specified range, repair the short to voltage as necessary. |
| ⇒ | If the DTC resets, replace the K20 Engine Control Module. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
| © Copyright Chevrolet. All rights reserved |
| © Copyright Chevrolet. All rights reserved |
