Cross-Reference Information for Diagnostic Codes
Table 1 is a list of the diagnostic codes for the engine. The diagnostic codes are cross-referenced with the appropriate procedure that can be used to troubleshoot the code.
Further explanations of diagnostic codes are explained after Table 1.
Portions of this material are reprinted with permission from SAE J1939DA_201607© 2016 SAE International. SAE International is not responsible for any use or translation of this material, in whole or in part. Please contact SAE International to obtain a complete copy of SAE J1939DA_201607, the official definitive source of this standard.
Cross-Reference from Diagnostic Trouble Codes to Functional Test or Procedure | ||
---|---|---|
J1939 Code and Description | CDL Code and Description | Troubleshooting Procedure |
91-3
Accelerator Pedal Position #1 : Voltage Above Normal |
91-3
Accelerator Pedal Position #1 : Voltage Above Normal |
Troubleshooting, "Speed Control - Test" |
91-4
Accelerator Pedal Position #1 : Voltage Below Normal |
91-4
Accelerator Pedal Position #1 : Voltage Below Normal |
Troubleshooting, "Speed Control - Test" |
91-8
Accelerator Pedal Position #1 : Abnormal Frequency, Pulse Width, or Period |
91-8
Accelerator Pedal Position #1 : Abnormal Frequency, Pulse Width, or Period |
Troubleshooting, "Speed Control - Test" |
95-2
Engine Fuel Filter Differential Pressure : Erratic, Intermittent, or Incorrect |
95-2
Engine Fuel Filter Differential Pressure : Erratic, Intermittent, or Incorrect |
The filtered fuel pressure is greater than the unfiltered fuel pressure. Ensure that the sensor connectors are connected to the correct sensors. If an electrical problem with a sensor is suspected, refer to Troubleshooting, "Sensor Signal (Analog, Active) - Test" for information that is related to troubleshooting an electrical problem with the fuel pressure sensors. |
99-2
Engine Oil Filter Differential Pressure Sensor : Erratic, Intermittent, or Incorrect |
99-2
Engine Oil Filter Differential Pressure Sensor : Erratic, Intermittent, or Incorrect |
The filtered oil pressure is greater than the unfiltered oil pressure. Ensure that the sensor connectors are connected to the correct sensors. If an electrical problem with a sensor is suspected, refer to Troubleshooting, "Sensor Signal (Analog, Active) - Test" for information that is related to troubleshooting an electrical problem with the oil pressure sensors. |
100-3
Engine Oil Pressure : Voltage Above Normal |
100-3
Engine Oil Pressure : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
100-4
Engine Oil Pressure : Voltage Below Normal |
100-4
Engine Oil Pressure : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
100-13
Engine Oil Pressure : Out of Calibration |
N/A | Troubleshooting, "Pressure Sensor - Calibrate" |
100-14
Engine Oil Pressure : Special Instruction |
N/A | This diagnostic 100-14 will come when minimum oil pressure threshold 20 kPa is not built within the prelube duration. If the oil pressure is less than 20 kPa, will cause 100-14. |
101-3
Engine Crankcase Pressure : Voltage Above Normal |
101-3
Crankcase Air Pressure Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
101-4
Engine Crankcase Pressure : Voltage Below Normal |
101-4
Engine Crankcase Pressure : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
101-13
Engine Crankcase Pressure : Out of Calibration |
101-13
Engine Crankcase Pressure : Out of Calibration |
Troubleshooting, "Sensor Calibration Required - Test" |
105-3
Engine Intake Manifold #1 Temperature : Voltage Above Normal |
172-3
Intake Manifold Air Temperature Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
105-4
Engine Intake Manifold #1 Temperature : Voltage Below Normal |
172-4
Intake Manifold Air Temperature Sensor : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
108-3
Barometric Pressure : Voltage Above Normal |
3528-3
Barometric Pressure Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
108-4
Barometric Pressure : Voltage Below Normal |
3528-4
Barometric Pressure Sensor : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
108-13
Barometric Pressure : Out of Calibration |
274-13
Atmospheric Pressure Sensor : Out of Calibration |
Troubleshooting, "Sensor Calibration Required - Test" |
108-21
Barometric Pressure : Data Drifted Low |
3528-21
Barometric Pressure Sensor : Data Drifted Low |
Troubleshooting, "Sensor Supply - Test" |
110-3
Engine Coolant Temperature : Voltage Above Normal |
110-3
Engine Coolant Temperature Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
110-4
Engine Coolant Temperature : Voltage Below Normal |
110-4
Engine Coolant Temperature Sensor : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
168-2
Battery Potential / Power Input #1 : Erratic, Intermittent, or Incorrect |
168-2
Electrical System Voltage : Erratic, Intermittent, or Incorrect |
Troubleshooting, "Electrical Power Supply - Test" |
168-3
Battery Potential / Power Input #1 : Voltage Above Normal |
168-3
Electrical System Voltage : Voltage Above Normal |
Troubleshooting, "Electrical Power Supply - Test" |
168-4
Battery Potential / Power Input #1 : Voltage Below Normal |
168-4
Electrical System Voltage : Voltage Below Normal |
Troubleshooting, "Electrical Power Supply - Test" |
190-8
Engine Speed : Abnormal Frequency, Pulse Width, or Period |
190-8
Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period |
Troubleshooting, "Speed/Timing - Test" |
626-5
Engine Start Enable Device 1 : Current Below Normal |
2417-5
Ether Injection Control Solenoid : Current Below Normal |
Troubleshooting, "Ether Starting Aid - Test" |
626-6
Engine Start Enable Device 1 : Current Above Normal |
2417-6
Ether Injection Control Solenoid : Current Above Normal |
Troubleshooting, "Ether Starting Aid - Test" |
630-2
Calibration Memory : Erratic, Intermittent, or Incorrect |
268-2
Programmed Parameter Fault : Erratic, Intermittent, or Incorrect |
Troubleshooting, "Configuration Parameters" |
631-2
Calibration Module : Erratic, Intermittent, or Incorrect |
253-2
Personality Module : Erratic, Intermittent, or Incorrect |
Troubleshooting, "ECM Software - Install" |
637-11
Engine Timing Sensor : Other Failure Mode |
261-11
Engine Timing Offset fault |
Troubleshooting, "Timing - Calibrate" |
651-5
Engine Injector Cylinder #01 : Current Below Normal |
1-5
Cylinder #1 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
651-6
Engine Injector Cylinder #01 : Current Above Normal |
1-6
Cylinder #1 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
652-5
Engine Injector Cylinder #02 : Current Below Normal |
2-5
Cylinder #2 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
652-6
Engine Injector Cylinder #02 : Current Above Normal |
2-6
Cylinder #2 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
653-5
Engine Injector Cylinder #03 : Current Below Normal |
3-5
Cylinder #3 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
653-6
Engine Injector Cylinder #03 : Current Above Normal |
3-6
Cylinder #3 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
654-5
Engine Injector Cylinder #04 : Current Below Normal |
4-5
Cylinder #4 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
654-6
Engine Injector Cylinder #04 : Current Above Normal |
4-6
Cylinder #4 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
655-5
Engine Injector Cylinder #05 : Current Below Normal |
5-5
Cylinder #5 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
655-6
Engine Injector Cylinder #05 : Current Above Normal |
5-6
Cylinder #5 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
656-5
Engine Injector Cylinder #06 : Current Below Normal |
6-5
Cylinder #6 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
656-6
Engine Injector Cylinder #06 : Current Above Normal |
6-6
Cylinder #6 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
657-5
Engine Injector Cylinder #07 : Current Below Normal |
7-5
Cylinder #7 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
657-6
Engine Injector Cylinder #07 : Current Above Normal |
7-6
Cylinder #7 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
658-5
Engine Injector Cylinder #08 : Current Below Normal |
8-5
Cylinder #8 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
658-6
Engine Injector Cylinder #08 : Current Above Normal |
8-6
Cylinder #8 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
659-5
Engine Injector Cylinder #09 : Current Below Normal |
9-5
Cylinder #9 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
659-6
Engine Injector Cylinder #09 : Current Above Normal |
9-6
Cylinder #9 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
660-5
Engine Injector Cylinder #10 : Current Below Normal |
10-5
Cylinder #10 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
660-6
Engine Injector Cylinder #10 : Current Above Normal |
10-6
Cylinder #10 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
661-5
Engine Injector Cylinder #11 : Current Below Normal |
11-5
Cylinder #11 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
661-6
Engine Injector Cylinder #11 : Current Above Normal |
11-6
Cylinder #11 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
662-5
Engine Injector Cylinder #12 : Current Below Normal |
12-5
Cylinder #12 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
662-6
Engine Injector Cylinder #12 : Current Above Normal |
12-6
Cylinder #12 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
663-5
Engine Injector Cylinder #13 : Current Below Normal |
13-5
Cylinder #13 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
663-6
Engine Injector Cylinder #13 : Current Above Normal |
13-6
Cylinder #13 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
664-5
Engine Injector Cylinder #14 : Current Below Normal |
14-5
Cylinder #14 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
664-6
Engine Injector Cylinder #14 : Current Above Normal |
14-6
Cylinder #14 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
665-5
Engine Injector Cylinder #15 : Current Below Normal |
15-5
Cylinder #15 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
665-6
Engine Injector Cylinder #15 : Current Above Normal |
15-6
Cylinder #15 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
666-5
Engine Injector Cylinder #16 : Current Below Normal |
16-5
Cylinder #16 Injector : Current Below Normal |
Troubleshooting, "Injector Solenoid - Test" |
666-6
Engine Injector Cylinder #16 : Current Above Normal |
16-6
Cylinder #16 Injector : Current Above Normal |
Troubleshooting, "Injector Solenoid - Test" |
678-3
ECU 8 Volts DC Supply : Voltage Above Normal |
41-3
8 Volt DC Supply : Voltage Above Normal |
Troubleshooting, "Sensor Supply - Test" |
678-4
ECU 8 Volts DC Supply : Voltage Below Normal |
41-4
8 Volt DC Supply : Voltage Below Normal |
Troubleshooting, "Sensor Supply - Test" |
723-8
Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width, or Period |
342-8
Secondary Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period |
Troubleshooting, "Speed/Timing - Test" |
1176-3
Engine Turbocharger 1 Compressor Inlet Pressure : Voltage Above Normal |
2738-3
Turbocharger #1 Compressor Inlet Pressure Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
1176-4
Engine Turbocharger 1 Compressor Inlet Pressure : Voltage Below Normal |
2738-4
Turbocharger #1 Compressor Inlet Pressure Sensor : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
1177-3
Engine Turbocharger 2 Compressor Inlet Pressure : Voltage Above Normal |
2739-3
Turbocharger #2 Compressor Inlet Pressure Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
1177-4
Engine Turbocharger 2 Compressor Inlet Pressure : Voltage Below Normal |
2739-4
Turbocharger #2 Compressor Inlet Pressure Sensor : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
1208-3
Engine Pre-filter Oil Pressure : Voltage Above Normal |
542-3
Engine Oil Pressure Sensor - Before Oil Filter : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
1208-4
Engine Pre-filter Oil Pressure : Voltage Below Normal |
542-4
Engine Oil Pressure Sensor - Before Oil Filter : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
1208-13
Engine Pre-filter Oil Pressure : Out of Calibration |
542-13
Engine Oil Pressure Sensor - Before Oil Filter : Out of Calibration |
Troubleshooting, "Sensor Calibration Required - Test" |
1656-2
Engine Automatic Start Enable Switch : Erratic, Intermittent, or Incorrect |
336-2
Engine Control Switch : Erratic, Intermittent, or Incorrect |
Troubleshooting, "Engine Control Switch - Test" |
2433-3
Engine Exhaust Manifold Bank #2 Temperature #1 : Voltage Above Normal |
828-3
Right Exhaust Temperature Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
2433-4
Engine Exhaust Manifold Bank #2 Temperature #1 : Voltage Below Normal |
828-4
Right Exhaust Temperature Sensor : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
2433-8
Engine Exhaust Manifold Bank #2 Temperature #1 : Abnormal Frequency, Pulse Width, or Period |
828-8
Right Exhaust Temperature Sensor : Abnormal Frequency, Pulse Width, or Period |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
2434-3
Engine Exhaust Manifold Bank #1 Temperature #1 : Voltage Above Normal |
827-3
Left Exhaust Temperature Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
2434-4
Engine Exhaust Manifold Bank #1 Temperature #1 : Voltage Below Normal |
827-4
Left Exhaust Temperature Sensor : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
2434-8
Engine Exhaust Manifold Bank #1 Temperature #1 : Abnormal Frequency, Pulse Width, or Period |
827-8
Left Exhaust Temperature Sensor : Abnormal Frequency, Pulse Width, or Period |
Troubleshooting, "Sensor Signal (Analog, Passive) - Test" |
3509-3
Sensor Supply Voltage 1 : Voltage Above Normal |
262-3
5 Volt Sensor DC Power Supply : Voltage Above Normal |
Troubleshooting, "Sensor Supply - Test" |
3509-4
Sensor Supply Voltage 1 : Voltage Below Normal |
262-4
5 Volt Sensor DC Power Supply : Voltage Below Normal |
Troubleshooting, "Sensor Supply - Test" |
3510-3
Sensor Supply Voltage 2 : Voltage Above Normal |
2131-3
5 Volt Sensor DC Power Supply #2 : Voltage Above Normal |
Troubleshooting, "Sensor Supply - Test" |
3510-4
Sensor Supply Voltage 2 : Voltage Below Normal |
2131-4
5 Volt Sensor DC Power Supply #2 : Voltage Below Normal |
Troubleshooting, "Sensor Supply - Test" |
3563-3
Engine Intake Manifold #1 Absolute Pressure : Voltage Above Normal |
1785-3
Intake Manifold Pressure Sensor : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
3563-4
Engine Intake Manifold #1 Absolute Pressure : Voltage Below Normal |
1785-4
Intake Manifold Pressure Sensor : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
3563-13
Engine Intake Manifold #1 Absolute Pressure : Out of Calibration |
1785-13
Intake Manifold Pressure Sensor : Out of Calibration |
Troubleshooting, "Sensor Calibration Required - Test" |
3563-21
Engine Intake Manifold #1 Absolute Pressure : Data Drifted Low |
1785-21
Intake Manifold Pressure Sensor : Data Drifted Low |
Troubleshooting, "Sensor Calibration Required - Test" |
4210-5
Engine Pre-lube Drive : Current Below Normal |
338-5
Engine Pre-Lube Pump Relay : Current Below Normal |
Troubleshooting, "Solenoid Valve - Test (Engine)" |
4210-6
Engine Pre-lube Drive : Current Above Normal |
338-6
Engine Pre-Lube Pump Relay : Current Above Normal |
Troubleshooting, "Solenoid Valve - Test (Engine)" |
4212-5
Fan Drive Bypass Command Status : Current Below Normal |
291-5
Engine Cooling Fan Solenoid : Current Below Normal |
Troubleshooting, "Cooling Fan Control - Test" |
4212-6
Fan Drive Bypass Command Status : Current Above Normal |
291-6
Engine Cooling Fan Solenoid : Current Above Normal |
Troubleshooting, "Cooling Fan Control - Test" |
4215-3
Ground-Level Shutdown Activated : Voltage Above Normal |
267-4
Remote Shutdown Input : Voltage Below Normal |
Troubleshooting, "Shutdown (Ground Level) - Test" |
4215-4
Ground-Level Shutdown Activated : Voltage Below Normal |
267-5
Remote Shutdown Input : Current Below Normal |
Troubleshooting, "Shutdown (Ground Level) - Test" |
5578-3
Engine Fuel Delivery Absolute Pressure : Voltage Above Normal |
289-3
Fuel Pressure Sensor - Before Fuel Filter : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
5578-4
Engine Fuel Delivery Absolute Pressure : Voltage Below Normal |
289-4
Fuel Pressure Sensor - Before Fuel Filter : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
5578-13
Engine Fuel Delivery Absolute Pressure : Out of Calibration |
289-13
Fuel Pressure Sensor - Before Fuel Filter : Out of Calibration |
Troubleshooting, "Pressure Sensor - Calibrate" |
5578-21
Engine Fuel Delivery Absolute Pressure : Data Drifted Low |
289-21
Fuel Pressure Sensor - Before Fuel Filter : Data Drifted Low |
Troubleshooting, "Sensor Supply - Test" |
5580-3
Engine Filtered Fuel Delivery Absolute Pressure : Voltage Above Normal |
460-3
Fuel Pressure Sensor - After Fuel Filter : Voltage Above Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
5580-4
Engine Filtered Fuel Delivery Absolute Pressure : Voltage Below Normal |
460-4
Fuel Pressure Sensor - After Fuel Filter : Voltage Below Normal |
Troubleshooting, "Sensor Signal (Analog, Active) - Test" |
5580-18
Engine Filtered Fuel Delivery Absolute Pressure : Low - moderate severity (2) |
E198(2)
Low Fuel Pressure |
Troubleshooting, "Fuel Pressure Is Low" |
5580-21
Engine Filtered Fuel Delivery Absolute Pressure : Data Drifted Low |
460-21
Fuel Pressure Sensor - After Fuel Filter : Data Drifted Low |
Troubleshooting, "Sensor Supply - Test" |
Diagnostic codes alert the operator that a problem in the electronic system has been detected. Diagnostic codes are also used by the service technician to identify the nature of the problem. Caterpillar Electronic Technician (ET) is a software program that runs on a personal computer. The software can be used by the service technician to view the diagnostic code information for an ECM. The diagnostic code will be displayed as a two-element code. The following terms describe the elements of the code:
Suspect Parameter Number (SPN) - The SPN is a code which is assigned to each component to identify data.
Failure Mode Identifier (FMI) - The FMI indicates the type of failure.
Refer to Table 1 for a complete list of the diagnostic codes and the appropriate troubleshooting procedure.
Note: Do not confuse diagnostic codes with event codes. Event codes alert the operator that an abnormal operating condition such as low oil pressure or high coolant temperature has been detected. If an event code is active, refer to Troubleshooting, "Event Codes".
Illustration 1 is an example of the operating range of a sensor.
Illustration 1 | g01365757 |
Example of the typical operating range of a sensor (1) This area represents the normal operating range of the engine parameter. (2) In these areas, the engine is operating in an unsafe operating range of the monitored parameter. An event code will be generated for the monitored parameter. The sensor circuit does not have an electronic problem. Refer to Troubleshooting, "Event Codes" for additional information on event codes. (3) In these areas, the signal from the sensor is outside of the operating range of the sensor. The sensor circuit has an electronic problem. A diagnostic code will be generated for the sensor circuit. |
An active diagnostic code represents a problem with the electronic control system. Correct the problem as soon as possible.
When the ECM generates an active diagnostic code. The "Active Alarm" indicator ("Control Alarm Status" on Cat ET) is activated to alert the operator. If the condition that generated the code is momentary, the message disappears from the list of active diagnostic codes. The diagnostic code becomes logged.
When the ECM generates a diagnostic code, the ECM logs the code in permanent memory. The ECM has an internal diagnostic clock. Each ECM will record the following information when a code is generated:
- The hour of the first occurrence of the code
- The hour of the last occurrence of the code
- The number of occurrences of the code
This information is a valuable indicator for troubleshooting intermittent problems.
A code is cleared from memory when one of the following conditions occur:
- The service technician manually clears the code.
- The code does not recur for 100 hours.
- A new code is logged and there are already ten codes in memory. In this case, the oldest code is cleared.
Some diagnostic codes may be easily triggered. Some diagnostic codes may log occurrences that did not result in complaints. The most likely cause of an intermittent problem is a faulty connection or damaged wiring. The next likely cause is a component failure. The least likely cause is the failure of an electronic module. Diagnostic codes that are logged repeatedly may indicate a problem that needs special investigation.
Note: Always clear logged diagnostic codes after investigating and correcting the problem which generated the code.