Diagnostic guide for P1168

Diagnostic Guide for P1168 - Closed Loop Control Function Bank 2

The P1168 code indicates a malfunction in the closed-loop control function for bank 2 of the engine. This guide aims to help diagnose the underlying issues causing this code, focusing on the air-fuel ratio sensor or heated oxygen sensor, depending on the vehicle model year.

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Difficulty

Intermediate

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Estimated Time

30-60 Minutes

Estimated Diagnostic Cost

$0-$100

Typical shop charge to perform this diagnostic process. Repair parts and labor are not included.

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Tools Needed

OBDII scanner, multimeter, wiring diagram, basic hand tools

Safety Notes

Ensure the engine is cool before working on exhaust components. Use caution when lifting the vehicle and during road tests. Wear safety glasses and gloves as needed.

Step 1

Check for Additional Codes

Instruction Use an OBDII scanner to check for any additional trouble codes that may be present.

Expected result A list of trouble codes, including P1168.

If Pass If only P1168 is present, proceed to the next step. If other codes are present, address those first as they may be related.

If Fail If P1168 is the only code, continue with the diagnostic process. If other codes are present, investigate those issues.

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Step 2

Inspect the Air Fuel Ratio Sensor/Heated Oxygen Sensor

Instruction Locate and visually inspect the air fuel ratio sensor (for 2005 and newer) or heated oxygen sensor (for older models) on bank 2 for any signs of damage or disconnection.

Expected result The sensor should be securely connected with no visible damage to the wiring or connectors.

If Pass If the sensor appears intact, proceed to test the sensor's electrical output.

If Fail If there is damage or disconnection, repair or replace the sensor as needed.

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Step 3

Test Sensor Voltage Output

Instruction Using a multimeter, measure the voltage output of the air fuel ratio sensor or heated oxygen sensor while the engine is running.

Expected result The voltage should fluctuate between 0.1V and 0.9V (for air fuel ratio sensors) or show a specific voltage range for heated oxygen sensors, depending on the model.

If Pass If the voltage is within the expected range, the sensor is likely functioning correctly. Proceed to check the wiring harness.

If Fail If the voltage is outside the expected range, the sensor may be faulty and should be replaced.

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Step 4

Inspect Wiring and Connectors

Instruction Check the wiring harness and connectors leading to the air fuel ratio sensor or heated oxygen sensor for any signs of damage, corrosion, or poor connections.

Expected result Wiring and connectors should be in good condition with no signs of wear or corrosion.

If Pass If the wiring is intact, proceed to check for continuity in the circuit.

If Fail Repair or replace any damaged wiring or connectors found during the inspection.

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Step 5

Check for Continuity in the Circuit

Instruction With the multimeter, check for continuity in the wiring circuit from the sensor to the ECM.

Expected result Continuity should be present without any breaks in the circuit.

If Pass If continuity is confirmed, the issue may lie within the ECM or its programming. Consider further diagnostics.

If Fail If there is no continuity, repair the wiring as necessary to restore the circuit.

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Step 6

Evaluate ECM Functionality

Instruction If all previous steps pass, consider testing the ECM for proper functionality, as it may not be processing the sensor signals correctly.

Expected result The ECM should be functioning correctly without faults.

If Pass If the ECM is functioning properly, further investigation may be needed into the vehicle's fuel system or air intake.

If Fail If the ECM is found to be faulty, replacement or reprogramming may be necessary.

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Coddy can help with this step only. Tell me what you tested or what result you got.