Infiniti QX4 Problems

RepairPal has identified the most common problems with the Infiniti QX4 as reported by actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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13
Known Problems

The 4WD light may flash on and off intermittently with no transfer case related fault code stored in the powertrain control module (PCM). Our technicians recommend to ensure the correct Nissan/Infiniti  approved fluid is present in the transfer case if this condition occurs.

Rattling and tapping in the front of the engine on the 2001-2004 Infiniti QX4 is very evident, especially on cold starts. This rattling noise should not be taken lightly as it warns of upcoming timing chain failure. 

The cause of the noise is faulty timing chain guide rails and timing chain tensioners that wear out well ahead of schedule. These components are there to keep the timing chain tight and properly positioned. When these parts fail, the timing chain becomes loose, and pieces of the timing chain guides break off, falling into the oil pan. 

To remedy the situation, Nissan/Infiniti has made revised guides and tensioners, but replacement can be very costly. 

Proper oil change intervals and oil type may help slow or prevent the situation. 

The throttle body for the Infiniti QX4 is known for carbon buildup, and requires regular, light cleaning to maintain peak performance. After cleaning the throttle body, many owners notice a very high idle, erratic (bouncing) idle, and unpredictable power surging. 

The cause is normal ECU adaptation: When the throttle body builds up carbon, the rate of airflow is slightly decreased. The vehicles computer reads this decrease in air volume, and adjusts the throttle body settings to maintain the proper engine idle speed. When the carbon is cleaned out, the ECU now registers too much air, and cannot adjust back to the original settings. While it is trying to change settings, the idle will bounce from low to high, and the car will surge forward at times. 

It has been recommended to simply wipe inside the throttle body every 12,000 miles, and never to touch the flap inside. Also, the cleaning procedure may be best left to a qualified technician.

The solution can be as simple as disconnecting the battery for at least an hour, having the dealer reset the computer, or, in extreme cases, replace the throttle bodies. 

The rear oxygen sensor may fail resulting in illumination of the Check Engine Light. Our technicians recommend to ensure the latest software is installed in the powertrain control module (PCM) along with replacing the failed O2 sensor.

Carbon deposits on the throttle body may cause any of the following issues: Idle speed fluctuation, incorrect idle speed, difficulty accelerating way from a stop, and or increased accelerator pedal resistance. Our technicians tell us a revised throttle body and associated parts are available to resolve this issue.

Front catalytic converters are prone to cracking along the seams of the converter itself. Most repair shops can successfully weld the seems to prevent exhaust leakage.

The heater blower motor may only work on the high speed setting. Our technicians recommend replacing the heater blower motor and fan control amplifier to address this problem.

Failure of the EVAP System charcoal canister may allow charcoal debris to infiltrate the EVAP system causing other failures. Cleaning the vapor lines to ensure the system is clear of debris is important when repairing EVAP system failures.

The Check Engine Light may illuminate indicating a fault with two or more oxygen sensors. Our technicians tell us this may be caused by a poor ground between the cylinder head and the exhaust manifold.

The Check Engine Light may illuminate with code P0138, P0140, P0158, and/or P0160 stored. Our technicians recommend replacing the rear oxygen sensor, and reprogramming the vehicle's powertrain control module (PCM) with upgraded software to correct this concern.

The mass airflow sensor may fail resulting in a loss of power and/or Check Engine Light illumination with code P0171 and/or P0174 stored. Our technicians recommend replacing the failed airflow sensor to correct this concern.

An abnormal noise may develop from the timing chain area, Our technicians tell us it may be necessary to replace the variable valve timing camshaft shaft sprockets to correct this concern.

The Check Engine Light may illuminate with throttle position switch fault codes stored. Our technicians tell us a revised throttle position switch is available to correct this concern.