How to Fix P1222 Code On 6.7L Cummins? (Fully Explained)

With different symptoms of Diagnostic Trouble Codes flashing before your eyes on the Cummins engine, it is impossible to correctly verify which one it is and what is causing it. Now, if you have possibly verified as code P1222, then you’re welcome here to read all about it.

The P1222 code on your 6.7 Cummins indicates Leak Detection During Motoring. In simple words, it means that the Engine Control Module (ECM) has found an inappropriate amount of fuel flow or fuel leakage in the fuel delivery system while the engine was running.

Don’t worry, folks! The code P1222, like any other, can be handled easily. Just take a few minutes to understand its causes, symptoms, solutions for fixing it, and associated costs.

P1222 Code On 6.7L Cummins

What Does Code P1222 Mean On 6.7 Cummins?

Let’s try to understand the code in simple terms. When the code is flashing, it indicates a leak in the fuel system. It runs when the ECM has detected an excessive fuel going into the rail instead of the injectors.

The extra fuel going out of the system could be reaching the cylinder or other mechanical parts. Whatever it is, the fuel delivery system is not operating as it should.

Hence, the system initiates a counter. And with the counter reaching a previously listed value, the ECM sets a fault allowing the engine to derate.

And in case the leak is undetectable, the counter counts down until it reaches zero; afterward, the engine starts running normally again.

So, what does the code P1222 stand for?

  • P= OBD-II Diagnostic Powertrain
  • 1 = Fuel and Air Metering
  • 2 = Turbocharger Boost Sensor A Circuit Low
  • 22 = Specific fault index (In our case, Heater Circuit ‘A’ Malfunction)

How Serious Is Code P1222 On 6.7 Cummins?

As we explained earlier, the P1222 deals with fuel leakage when the engine is running. When the engine is running, a certain amount of natural leakage occurs.

To overcome that, only a small amount of fuel is delivered by rail. With the P1222 code set up, the fuel flow has crossed an expected value detected by the ECM.

When such leaks occur, it can result in several troubles, including a deterioration in the engine efficiency and low fuel economy, and ultimately it can result in power loss.

I’m pretty sure you know what the power loss means? Yes, walking home towing your vehicle because it’s unable to start. And this is what happens when the P1222 code is not handled timely.

What Causes P1222 Code On 6.7 Cummins?

There are several reasons behind the code P1222 showing up, the primary cause being a failure in one of the injectors or a faulty ECM/PCM. Let’s get you a list of all the possible reasons behind it-

  • Reprogrammed Powertrain Control Module (PCM)
  • Malfunctioning Fuel Injector
  • The poor electrical connection of the Fuel Injector circuit
  • Open or shorted Fuel Injector harness
  • Defective throttle drive gear
  • Defective oil control valve
  • Dirty or low oil level in the engine

Other Symptoms Of Getting Code P1222 On 6.7 Cummins

So, how will you detect a probable P1222 code running on the engine? The primary symptom will be the check engine light or the WTS light (Wait to Start) coming on frequently. Besides this, a couple of msignstoms help you verify P1222. Such as-

  • Misfiring or sudden halting of the engine
  • Car taking time to start or not starting at all
  • Decreased fuel economy
  • Engine performance downfall
  • Dash binger going off again and again

How To Fix Code P1222 On 6.7 Cummins?

All these codes and so many tools at hand, but of course, you can’t be sure how to fix all of them, no matter if you are an expert in repairing automobiles. The first step is to diagnose the code correctly and then move on to the required solutions. Let’s see

Step 1: Diagnosis

The first and foremost step is to diagnose if there is a code P1222. Let’s see how to do it.

High-pressure relief testing:

You need an advanced scan tool for this step. It detects the open valve by monitoring the actual pressure and also looks for the drop.

Fuel control actuator testing:

The suction control valve or the Injection pressure regulator is tested by commanding it to check if it can reach the maximum fuel pressure. If it does, then the actuator is fine!

Fuel injector testing:

A unique tool, mainly a modified Banjo fitting, is used to check the return flow. The device is installed into the fuel return hoses, which connect to the fuel filter or injection pump. The test results shouldn’t give more than 180ml/min in the injectors; if it does, you have a faulty injector.

Step 2: Fuel Injector Wire Repair

Before anything else, you need to ensure the fuel injector’s wire connections are fine. If you detect wear out or burns in any of the wires, repair them or replace them with new ones.

Step 3: Correction of Open Circuit of Injector

If the wires seem fine, move on to inspecting the electrical circuit connections of the injector. Now, do you see any shorted or open circuits? If you do, make the necessary corrections to sort out the circuit issue.

Step 4: Fuel Injector Replacement

There could be blockages in your fuel injector 1. If you find out that it has damaged the injector, replace it with no delay.

How Much Does It Cost To Fix 6.7 Cummins P1222 Code?

If you think you’ll just end up worsening your engine condition by messing up the steps, it’s relatively safe to take it to a professional mechanic. The time for fixing the code P1222 would take about an hour. The hourly labor cost for a mechanic is about $75 to $100, depending on the vehicle and engine type, the geographical location, and a few other factors.

When you have a malfunctioning engine injector, the cost of buying a new one will range from about $40 to $150.

Now, although the failure of the PCM isn’t expected. But in this case, if it does fail. You’ll just have to get a new one that’ll cost you about $800.

Can You Drive Your 6.7 Cummins With Code P1222?

With the code P1222 flashing, there is an issue with the fuel system, particularly with the plug wire sequence in the circuit. As a result, the engine will frequently misfire; it can even run with a start-and-stop motion. And finally, the vehicle may halt running at all.

If this proceeds and your vehicle keeps stopping, the engine performance will deteriorate. Ultimately, you might even cause irretrievable damage to the engine, causing your vehicle’s life to be in jeopardy as well.


Your Dodge with a Cummin 6.7 is a precious automobile, and different codes like the P1222 flashing on the engine will indeed worry you. But trust us, you need not sweat about it and follow this troubleshooting guide thoroughly to get an idea about the code.

We would like to advise you to take your engine to a reputed automobile store or get a mechanic to check it as soon as you spot the issues.

Of course, you do not want to be lazy and sit down with P1222 code symptoms popping up every time. Hence, run to the mechanic or sort it yourself for the sake of your Cummins and your wallet, saving you the extra cost for further damage.

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