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DTC P2237 or P2238 — LNP or LNQ

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 P2237 00: HO2S Pump Current Control Circuit Sensor 1

DTC P2238 00: HO2S Pump Current Control Circuit Low Voltage Sensor 1

Diagnostic Fault Information

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

-

-

Circuit/System Description

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.

Conditions for Running the DTC

P2237 00

    • 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.

P2238 00

    • 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.

Conditions for Setting the DTC

P2237 00

    • 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.

P2238 00

    • 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.

Action Taken When the DTC Sets

DTCs P2237 00 and P2238 00 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P2237 00 and P2238 00 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Heated Oxygen Sensor Wiring Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Clear the DTCs with a scan tool.
  2. Operate the vehicle within the conditions for running and setting the DTC. The DTC should not set.
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

  1. Ignition OFF, disconnect the harness connector at the B52 Heated Oxygen Sensor.
  2. Disconnect the X1 harness connector at the K20 Engine Control Module
  3. Test for less than 5 Ω between both the harness connectors on the terminals as listed below:
  4. • 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
  5. Test for infinite resistance between each B52 Heated Oxygen Sensor circuit terminal and ground.
  6. If less than the specified value, repair the short to ground as necessary.
  7. Test for infinite resistance between each B52 Heated Oxygen Sensor circuit terminals.
  8. If less than the specified value, repair as necessary.
  9. Ignition ON, test for less than 0.3 V between each B52 Heated Oxygen Sensor circuit terminal and ground.
  10. If greater than the specified range, repair the short to voltage as necessary.
  11. If all circuits test normal, replace the B52 Heated Oxygen Sensor and verify the DTC does not reset
  12. If the DTC resets, replace the K20 Engine Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heated Oxygen Sensor Replacement
    • Control Module References for ECM replacement, setup, and programming
   


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