8M0021914 Mariner PIN , (.125 x 30 mm)

Probable Causes
Diagnostic codes
Throttle position sensor
Air intake and exhaust system
Fuel supply
Low compression (cylinder pressure)
Individual malfunctioning cylinderRecommended Actions
Diagnostic Codes
Use one of the following methods to check for active diagnostic codes:
The electronic service tool
The display on the control panelElectronic Service Tool
Connect the electronic service tool to the diagnostic connector.
Check for active diagnostic codes on the electronic service tool.
Investigate any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code". Display on the Control PanelNote: The following procedure is only applicable if the application is equipped with a display on the control panel.
Check the display on the control panel for active diagnostic codes.
Troubleshoot any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code". Throttle Position Sensor
Use the electronic service tool to observe the signal for the throttle position sensor. Make sure that the throttle reaches the 100% raw position and the calibrated position.
If the signal is erratic, refer to Troubleshooting, "Analog Throttle Position Sensor Circuit - Test".
If the repairs do not eliminate the fault, proceed to "Air Intake and Exhaust System". Air Intake and Exhaust System
Check the air filter restriction indicator, if equipped.
Ensure that the air filter is clean and serviceable.
Check the air intake and exhaust systems for the following defects:
Blockages
Restrictions
Damage to lines or hoses
If the repairs do not eliminate the fault, proceed to "Fuel Supply". Fuel Supply
Visually check the fuel tank for fuel. The fuel gauge may be faulty.
Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
If the temperature is below 0 °C (32 °F), check for solidified fuel (wax).
If equipped, check the water separator for water in the fuel.
Check for fuel supply lines that are restricted.
Check that the low-pressure fuel lines are tight and secured properly.
If equipped, replace the in-line fuel strainer.
Check that the Electric Fuel Lift Pump (EFLP) is operating. If the EFLP is suspect, refer to Troubleshooting, "Fuel Pump Relay Circuit - Test".
Replace the main fuel filters. If equipped, replace the fuel pre-filter.
Check the diesel fuel for contamination. Refer to Systems Operation, Testing, and Adjusting, "Fuel Quality - Test".
Check for air in the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Air in Fuel - Test".
Ensure that the fuel system has been primed. Refer to Systems Operation, Testing, and Adjusting, "Fuel System - Prime".
If the fault is not eliminated, refer to "Low Compression (Cylinder Pressure)". Low Compression (Cylinder Pressure)
Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test ".
If low compression is noted on any cylinders, investigate the cause and rectify the cause. Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Perform all necessary repairs.
Ensure that the repairs have eliminated the faults.
If no faults are detected, proceed to "Individual Malfunctioning Cylinders". Individual Malfunctioning Cylinders
With the engine speed at a fast idle, use the electronic service tool to perform the manual "Cylinder Cut Out Test". As each cylinder is cut out, listen for a change in the sound from the engine. When a cylinder is cut out, there should be a noticeable change in the sound of the engine. If a change in the sound of the engine is not noted, the isolated cylinder is not operating under normal conditions. If a change in the sound of the engine is less noticeable, the cylinder may be operating below normal performance. Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.
If the fault is not eliminated, contact the Technical Communicator at a Cat® dealer.