6.7L Cummins Common Problems and How to Fix Them

No system is flawless, and despite a most beneficial and somewhat faded reputation, the Cummins turbo diesel found in 1989 to the new Dodge/Ram vehicles is not without any glitches, annoyances, and sometimes even weak design features.

While some of the alarming situations and critical weaknesses mentioned here do not involve a coincidence with the Cummins engine, they still add to vehicle reliability issues.

Here are the typical problems found in Cummins fitted Dodge and Ram pickups.

The motor won’t start

It’s annoying when the car doesn’t run. You’re going to change the key and nothing is going to happen. About every driver of the vehicle has witnessed this.

There are a lot of things that can go wrong with your car, but there’s no need to panic, there’s a solution to almost any issue. Of course, you should contact the local vehicle association or towing service and get your vehicle towed to a reliable repair center.

The mechanism that goes forward from the period you insert the key in the ignition to the stage where the engine is going requires a few steps. When you know which step things are going wrong, you’ll have a great idea why your car won’t run.

What’s to search first

If the vehicle doesn’t start, first verify the basics:

Is the battery all right? Study the next paragraph about how to search the battery.
If the vehicle doesn’t start only with automatic transmission in “Park,” it begins with “Neutral” Often the car doesn’t start in “Park” but starts in “Neutral” because of such a problem with a neutral security turn. Learn more about the neutral safety turn here: how the auto start system operates.
Are the battery wires tight and non-corroded?
Do you believe there’s enough diesel in the tank? It’s a normal case where the fuel gauge doesn’t work properly and the vehicle is running out of fuel with the fuel gauge still displaying some fuel on board. There is no way to verify the fuel level other than the fuel gauge. But you should guess how long you’ve been traveling after the last refill.
Is the “Security” or key-shaped light in the instrument cluster still on or flashing?
Does your car have an anti-theft feature that doesn’t encourage the car to be started for any reason?

How to test your battery

A drained or dead battery is one of the potential explanations for not starting a vehicle. Often we either fail to turn off the dome light or anything else, or there could be a defective aspect of the car’s electrical system that draws the battery down.

Often, if the battery were old, it will only die one day, even if it was OK the day before. In this case, if the voltage is depleted on fuel, it may not have enough power to turn the engine over: you can hear a grinding noise, or the starter can turn very slowly when trying to start the engine.

The key will not turn on the ignition

If the key does not turn in the ignition, it may be for a few reasons: this sometimes occurs when the steering is locked by the ignition lock with the front wheels turned away (e.g. when parking on a hill) or when one of the front wheels is pressed into something (e.g. curb stone).

In this situation, attempt to turn the steering wheel left and right while softly jiggling the ignition key-this could help to loosen the steering lock.

Another explanation is that there’s a problem with the ignition lock or the key itself. This happens; the key and the lock system are worn over time. Try using a spare key. If nothing works, the nearest dealer is the safest way to go.

No lighting on the instrument panel

When you turn on the ignition and there are no lights on the instrument panel, this means that there is no electricity coming from the tank. It could be a faulty battery, or a bad ignition switch could trigger it.

Turn on the headlights, whether they are running, means that the battery has power or that the fault may be with the ignition switch or the wiring between the ignition switch and the battery.

If there are no lights on the dash and no other electrical consumers are running, the battery may be absolutely dead or there is no link between the battery and the vehicle’s electrical device. Check that the battery terminals look tight. If the battery is absolutely dead, you might want to jump start.

Safety’ or key-shaped light remains on or shines on the dashboard

Safety light flashes vehicles are fitted with an ignition coil or a security device that causes the engine to start unless the right key is used. More detail about the immobilizer can be found in the user manual.

This means that the ignition key has a chip inside with the security code. When you put it into the ignition, the security device sensor reads the code.

Usually, when you switch the ignition on, you will see a “Security” light turning on for a brief while, and then it will come off. It would mean that the code in the ignition key is right, and the vehicle is allowed to start.

The light of the “check engine” does not turn on

Checking Engine Light Once you turn the ignition on it before starting the vehicle, the “Check engine” lighting is expected to come on signaling that the engine processor (also called ECM, PCM, or ECU) is turned on.

If the “Check Engine” light doesn’t quite arrive with the ON ignition, it is likely that there is no power going to the engine computer (e.g. due to broken cable, defective key relay, blown fuse) or that there is a problem with the engine system function.

The motor cranks increasingly slower instead clicks

When the engine cranks slowly and slower until it works, the starter engine does not have enough power to turn the engine over. This issue should be reasonably important to identify since there are only two cables (positive and negative) to transmit the electrical current from the battery to the starter motor.

Again, the most important issue in this situation is a very small battery. Poor starter engines may also trigger this problem. Of course, weak communication or damage at the battery terminals or bad battery cables may also trigger these symptoms. If the battery is really old, you might want to completely replace the battery.

Related: How to Change Serpentine Belt on 6.7 Cummins

Common error codes

When operating on Cummins engines that are infused with Common-Rail (2003 Still will and higher), you can experience P0251 diagnostic trouble code. The customer’s concern is typically a lack of control when the truck is in a rough pull, particularly when it’s being towed.

Below are typical engine light problem codes for Dodge Cummins diesel engine. This database has been revised and included 2010 Dodge Cummins 6.7L diesel diagnostic difficulty codes.

P0008 ENGINE POSITION SYSTEM PERFORMANCE BANK 1
P000F FUEL SYSTEM OVER PRESSURE RELIEF VALVE ACTIVATED
P0016 CRANKSHAFT/CAMSHAFT TIMING MISALIGNMENT – BANK 1 SENSOR 1
P0030 O2 SENSOR 1/1 HEATER CIRCUIT OPEN
P0031 O2 SENSOR 1/1 HEATER CIRCUIT LOW
P0032 O2 SENSOR 1/1 HEATER CIRCUIT HIGH
P0036 O2 SENSOR 1/2 HEATER CIRCUIT OPEN
P0037 O2 SENSOR 1/2 HEATER CIRCUIT LOW
P0038 O2 SENSOR 1/2 HEATER CIRCUIT HIGH
P003A TURBOCHARGER BOOST CONTROL MODULE POSITION EXCEEDED LEARNING LIMIT
P0046 TURBOCHARGER BOOST CONTROL CIRCUIT PERFORMANCE
P0049 TURBOCHARGER TURBINE OVERSPEED
P0053 O2 SENSOR 1/1 HEATER RESISTANCE
P0054 O2 SENSOR 1/2 HEATER RESISTANCE
P006E TURBOCHARGER BOOST CONTROL MODULE SUPPLY VOLTAGE CIRCUIT LOW
P006F TURBOCHARGER BOOST CONTROL SUPPLY VOLTAGE CIRCUIT HIGH
P0071 AMBIENT AIR TEMPERATURE SENSOR PERFORMANCE
P0072 AMBIENT AIR TEMPERATURE SENSOR CIRCUIT LOW
P0073 AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH
P007B CHARGE AIR COOLER TEMPERATURE SENSOR CIRCUIT PERFORMANCE
P007C CHARGE AIR COOLER TEMPERATURE SENSOR CIRCUIT LOW
P007D CHARGE AIR COOLER TEMPERATURE SENSOR CIRCUIT HIGH
P007E CHARGE AIR COOLER TEMPERATURE SENSOR CIRCUIT INTERMITTENT/ERRATIC
P0087 FUEL RAIL PRESSURE TOO LOW
P0088 FUEL RAIL PRESSURE TOO HIGH
P00AF TURBOCHARGER BOOST CONTROL MODULE PERFORMANCE
P0101 MASS AIR FLOW SENSOR “A” CIRCUIT PERFORMANCE
P0102 MASS AIR FLOW SENSOR “A” CIRCUIT LOW
P0103 MASS AIR FLOW SENSOR “A” CIRCUIT HIGH
P0103 MASS AIR FLOW SENSOR “A” CIRCUIT HIGH
P0106 MANIFOLD ABSOLUTE PRESSURE SENSOR PERFORMANCE
P0107 MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT LOW
P0108 MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT HIGH
P0111 INTAKE AIR TEMPERATURE SENSOR 1 PERFORMANCE
P0112 INTAKE AIR TEMPERATURE SENSOR 1 CIRCUIT LOW
P0113 INTAKE AIR TEMPERATURE SENSOR 1 CIRCUIT HIGH
P0116 ENGINE COOLANT TEMPERATURE SENSOR PERFORMANCE
P0117 ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT LOW
P0118 ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT HIGH
P0128 THERMOSTAT RATIONALITY
P0131 O2 SENSOR 1/1 CIRCUIT LOW
P0135 O2 SENSOR 1/1 HEATER PERFORMANCE
P0137 O2 SENSOR 1/2 CIRCUIT LOW
P0138 O2 SENSOR 1/2 CIRCUIT HIGH
P013A O2 SENSOR 1/2 SLOW RESPONSE – RICH TO LEAN
P013B O2 SENSOR 1/2 SLOW RESPONSE – LEAN TO RICH
P0141 O2 SENSOR 1/2 HEATER PERFORMANCE
P0148 FUEL DELIVERY ERROR
P014C O2 SENSOR 1/1 SLOW RESPONSE – RICH TO LEAN
P014D O2 SENSOR 1/1 SLOW RESPONSE – LEAN TO RICH
P0169 WATER IN FUEL DETECTED FOR TOO LONG
P0191 FUEL RAIL PRESSURE SENSOR CIRCUIT PERFORMANCE
P0192 FUEL PRESSURE SENSOR LOW
P0193 FUEL PRESSURE SENSOR HIGH
P0201 FUEL INJECTOR 1 CIRCUIT/OPEN
P0202 FUEL INJECTOR 2 CIRCUIT/OPEN
P0203 FUEL INJECTOR 3 CIRCUIT/OPEN
P0204 FUEL INJECTOR 4 CIRCUIT/OPEN
P0205 FUEL INJECTOR 5 CIRCUIT/OPEN
P0206 FUEL INJECTOR 6 CIRCUIT/OPEN
P020A FUEL INJECTOR 1 PERFORMANCE
P020B FUEL INJECTOR 2 PERFORMANCE
P020C FUEL INJECTOR 3 PERFORMANCE
P020D FUEL INJECTOR 4 PERFORMANCE
P020E FUEL INJECTOR 5 PERFORMANCE
P020F FUEL INJECTOR 6 PERFORMANCE
P0216 – Injection Timing Control Circuit Malfunction
P2016 – Intake Manifold Runner Position Sensor/Switch Circuit Low Bank 1
P0217 COOLANT TEMPERATURE TOO HIGH
P0218 HIGH TEMPERATURE OPERATION ACTIVATED
P0219 ENGINE OVERSPEED
P0251 INJECTION PUMP FUEL VALVE FEEDBACK
P0253 INJECTION PUMP FUEL CONTROL CIRCUIT LOW
P0751 SHIFT SOLENOID A PERFORMANCE
P0755 2C SOLENOID CIRCUIT
P0756 SHIFT SOLENOID B PERFORMANCE
P0760 OD SOLENOID CIRCUIT
P0761 SHIFT SOLENOID C PERFORMANCE
P0765 UD SOLENOID CIRCUIT
P0766 SHIFT SOLENOID D PERFORMANCE
P0770 4C SOLENOID CIRCUIT
P0776 PRESSURE CONTROL SOLENOID B PERFORMANCE
P0778 PRESSURE CONTROL SOLENOID B CIRCUIT
P0796 PRESSURE CONTROL SOLENOID C PERFORMANCE
P0798 PRESSURE CONTROL SOLENOID C CIRCUIT
P0838 FOUR WHEEL DRIVE (4WD) SWITCH CIRCUIT LOW
P0839 FOUR WHEEL DRIVE (4WD) SWITCH CIRCUIT HIGH
P1277 STARTER CONTROL CIRCUIT 2 LOW
P1278 STARTER CONTROL CIRCUIT 2 HIGH
P1279 STARTER CONTROL CIRCUIT 2 OPEN
P127A STARTER CONTROL CIRCUIT 2 OVERCURRENT
P127C FUEL PUMP CONTROL CIRCUIT 2 LOW
P127D FUEL PUMP CONTROL CIRCUIT 2 HIGH
P127E FUEL PUMP CONTROL CIRCUIT 2 OPEN

Conclusion

It’s a very simple screening procedure. Unplug the two-wire connections of the ignition switch regulator and scan for white control with red streak wire.

Place the test light in the connector pin and turn someone on the starter motor to the run position. The test light is expected to turn on and stay on for a few seconds, and then go off. If that occurs, suspect a poor regulator, since the ECU feature is functioning properly.

If the test lamp does not come on within roughly 20 seconds, there could be a wiring issue or a potential ECU problem. But beware, the vehicle would need to be put on a test drive in order to check the allegation.

Related: Best Fuel Filter for 6.7 Cummins