P1168 – Closed Loop Control Fault (Nissan)

Description

P1168 on Nissan vehicles indicates that the engine control system is unable to achieve normal closed-loop air-fuel control for one cylinder bank under the required operating conditions. The fault is commonly associated with the upstream air-fuel ratio or heated oxygen sensor circuit, sensor heater operation, wiring or connectors. Diagnosis should confirm the affected bank and circuit for the specific Nissan model before any sensor is replaced.

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Symptoms

Check Engine Light may be on
Fuel economy may decrease
Engine may run rough or hesitate
Air-fuel mixture may remain incorrect
Additional air-fuel ratio or oxygen sensor codes may be stored
Symptoms may be mild or not noticeable

Causes

Open or short circuit in the upstream air-fuel ratio or oxygen sensor wiring
Faulty upstream air-fuel ratio or heated oxygen sensor
Faulty sensor heater circuit
Corroded or loose sensor connector
Power supply or ground fault in the sensor circuit
Related air-fuel ratio sensor fault stored with P1168
ECM calibration or software issue on specific Nissan models

Diagnosis

Read and record all stored and pending fault codes
Check freeze-frame data and note the operating conditions when P1168 was stored
Identify the affected bank and upstream sensor for the specific Nissan model
Check live data from the upstream air-fuel ratio or oxygen sensor
Inspect the sensor connector and wiring for damage, corrosion or loose terminals
Check the sensor heater power supply and ground circuit
Test the sensor signal circuit for open or short circuits
Diagnose any accompanying air-fuel ratio or oxygen sensor codes before replacing components
Follow the Nissan-specific diagnostic procedure for the vehicle and engine

Repair

Repair damaged wiring, terminals or connectors
Repair sensor heater power supply or ground faults
Repair open or short circuits in the sensor signal wiring
Replace the upstream air-fuel ratio or oxygen sensor only if testing confirms it is faulty
Diagnose and repair accompanying air-fuel ratio or oxygen sensor faults
Apply Nissan-specific ECM software updates only when required by the applicable service information