Troubleshooting the 6.7 Cummins No Start No Codes Problem

The 6.7 Cummins is not starting due to an unknown issue, and there are no diagnostic trouble codes present.

6.7 Cummins No Start No Codes

A 6.7 Cummins no-start no-codes situation can be perplexing on the surface, but by understanding the details, a successful solution may be found. Diesel fuel-injected engines can be affected by a number of issues related to starting, like fuel supply, sensors and electronic components. On a 6.7 Cummins engine, no-start conditions often occur when there is a weak or non-existent connection to the starter or an issue related to air intake. As there will likely be no codes, other issues may need to be investigated further such as fuel pressure, glow plugs and turbocharger performance. To solve the problem it is important to inspect all necessary components, first checking for common problems that exist with this particular engine type and then progressing with deeper diagnostics if needed. With a detailed inspection and troubleshooting effort needed in these cases, fix rates are typically higher than average and require careful consideration from an experienced technician who knows their way around diesel engines.


The fuel system is the first area to check when diagnosing a no-start condition on the 6.7L Cummins. The fuel must be free of contaminants and in good condition, otherwise it will not provide sufficient fuel pressure and volume to allow the engine to start. The lift pump must be able to maintain a minimum of 10 psi when running, and at least 9 psi when cranking. If the lift pump is not able to maintain the required pressure, then it should be replaced. Additionally, all of the fuel lines must be checked for any leaks or blockages that could impede fuel flow. The fuel filter must also be replaced if necessary.


The battery must also be in good condition in order for the 6.7L Cummins to start properly. The battery should have a minimum voltage of 12 volts when cranking and should not drop below 9 volts during cranking. If the battery voltage drops too low, then it could cause a no-start condition due to lack of power being supplied to all of the engine’s components, including the glow plugs and ECU. Additionally, all of the connections should be checked for corrosion or loose connections which could impede power delivery from the battery to other components in the system.

Glow Plugs

Glow plugs are vital for cold weather starting on 6.7L Cummins engines as they help preheat the combustion chamber before starting so that fuel can ignite quickly and easily once cranking begins. The glow plug system should be tested with an ohm meter, or with a specialized tool such as a glow plug tester that can measure current draw through each individual glow plug while cranking. A failed glow plug will show an open circuit when tested with an ohm meter or no current draw on a specialized tester due to lack of resistance in its heating element. If any of these tests reveal faulty glow plugs then they should be replaced immediately before attempting another start attempt as this could help resolve any no-start issues related to cold weather starting issues on 6.7L Cummins engines quickly and easily without needing additional diagnosis or repairs..


Injectors play an important role in providing adequate amounts of fuel for combustion on 6.7L Cummins engines so they must also be tested for proper operation if experiencing no-start conditions with no codes present during diagnosis using OBD II scan tools or code readers.. Injector operation can typically be tested using specialized tools such as an injector tester which measures leak off rates between each injector and its corresponding injector line while under pressure from an external source such as shop air supply lines (not engine compression). Additionally, injectors can also have their electrical signals checked with OBD II scan tool software while cranking by watching individual cylinder pulse widths which indicate proper electrical signals being sent from ECU/PCM to each injector connector at each cylinder location.. If any issues are found here then either faulty wiring harnesses need replacing or faulty injectors need replacing depending upon what is found during testing procedures..

Camshaft Position Sensor

The camshaft position sensor is responsible for providing accurate timing information regarding camshaft position relative to piston position so that ignition timing can occur appropriately during engine operation on all modern diesel engines including 6.7L Cummins engines.. This sensor must provide accurate information for spark timing events otherwise misfires will occur which can lead to difficult starting conditions due lack of adequate compression being generated by pistons firing at incorrect times within their cycles due improper spark timing events occurring from incorrect data from camshaft position sensors.. To test this sensors accuracy, one must use manufacturer specific diagnostic tools such as those available from Chrysler/Dodge/Jeep dealerships since these are required in order to accurately measure camshaft position relative piston position using specialized software designed specifically for this purpose.. Once this data is collected, any discrepancies between expected values versus actual values seen on diagnostic equipment can pinpoint precisely where problems lie regarding inaccurate data being provided by camshaft position sensors which may lead directly into causes behind difficult starting conditions such as those experienced on 6.7L Cummins engines with no codes present during diagnosis via OBD II scan tools or code readers..

Crank, No Start Basics

If you have a 6.7 Cummins that won’t start, the first thing to check is the basics: fuel, air and spark. Make sure that all of these components are working properly. If one of them is not functioning correctly, the engine won’t start.

Check Fuel System

The fuel system on a 6.7 Cummins is composed of several components including the fuel pump, injectors, and filters. Check to make sure that each of these components is working properly and that there are no leaks or blockages in the system.

If the fuel system checks out, then check the air intake system for any blockages or issues with airflow. The air intake system includes the air filter and turbocharger, so make sure those components are functioning properly as well.

Check Spark

After checking both the fuel and air systems, it’s time to check for spark. If there is no spark coming from the spark plugs then it could be a problem with either the ignition coils or spark plug wires. Check both for any signs of wear or damage and replace if necessary.

No Codes?

If you’re still not getting any codes from your 6.7 Cummins then it could be a problem with either your ECU or wiring harnesses. First check all of your wiring harnesses to make sure they’re connected properly and not damaged in any way. If everything looks good then it could be a problem with your ECU which will require professional assistance to diagnose and repair.

FAQ & Answers

Q: What could be the cause of a 6.7 Cummins not starting with no codes?
A: There are a few potential causes for a 6.7 Cummins not starting with no codes. It could be related to fuel delivery issues, such as a clogged or faulty fuel filter or air in the fuel lines. It could also be an issue with the starter, battery, or ignition system. Another possibility is an issue with the computer system or sensors that regulate engine timing and performance.

Q: How do you troubleshoot a 6.7 Cummins no start?
A: To troubleshoot a 6.7 Cummins no start, the first step is to perform a visual inspection of the engine and associated components. Look for signs of damage or wear and tear, check all connections and wiring harnesses, and inspect fuel filters and air intake components for any blockages or clogs that may be preventing air or fuel from reaching the engine. Once this is done, check for power at the starter solenoid and battery connections to ensure they are providing adequate power to start the engine. If necessary, use a scan tool to check for fault codes in the computer system.

Q: How do you diagnose an intermittently no start on a 6.7 Cummins?
A: To diagnose an intermittently no start on a 6.7 Cummins, first inspect all connections and wiring harnesses for any signs of damage or wear and tear that may be causing intermittent electrical issues. Also check all fuel filters and air intake components for any blockages that could prevent air or fuel from entering the engine as needed. If necessary, use a scan tool to read fault codes stored in the computer system related to engine timing and performance issues that may cause intermittent starts when driving conditions are different than normal operating conditions.

Q: What are some common causes of 6.7 Cummins hard starting?
A: Some common causes of 6.7 Cummins hard starting include worn out spark plugs, clogged fuel filters, faulty injectors, low-quality fuel being used in the engine, incorrect timing settings on the computer system or sensors regulating engine timing, problems with ignition system components such as coils and spark plugs, low levels of antifreeze in coolant tank causing insufficient lubrication to internal parts of engine during cold starts ,or problems with battery connections not providing enough current for starter motor operation during cold starts .

Q: How do I reset my 6.7 Cummins after replacing parts?
A: After replacing parts on your 6.7 Cummins its important to reset your ECU (Engine Control Unit) so that it can relearn new parameters after new parts have been installed or replaced on your vehicles drivetrain system including transmission and driveline systems . The best way to reset your ECU is by using an OBD-II scanner/reader which can be bought online at auto supply stores like AutoZone online store . Once you connect your scanner/reader device into your vehicle’s OBD-II port , it will allow you access into your vehicle’s onboard diagnostic trouble code (DTC) menu where you can manually reset your ECU settings back to factory defaults which will help ensure optimal performance after new parts have been installed onto your drivetrain systems .

The 6.7 Cummins No Start No Codes issue can be caused by a variety of factors, ranging from fuel system issues to electrical problems. Troubleshooting the issue requires a comprehensive approach that involves testing and diagnosing the various components that make up the engine. Once the source of the problem is identified, it should be addressed as soon as possible to keep the engine running properly and avoid further damage or malfunction.

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