P0068: P0068 Diagnostic Guide

What this code means

P0068 may mean the PCM is seeing airflow or load information that does not agree with throttle position.

What the vehicle may do

The vehicle may turn on the check engine light.
The engine may have possible rough running, hesitation, or reduced power depending on the fault.

Possible fault areas

Possible intake air system leak
Possible PCV or vacuum system leak
Possible engine sealing leak
Possible crankcase pressure sensor circuit concern
Possible crankcase pressure sensor concern
Possible PCM involvement

Diagnostic path

Open on P0068 diagnostic direction

On this F-150 2.7 EcoBoost, P0068 means the PCM may be seeing an airflow and load relationship that does not line up with throttle position. The truck may have a check engine light, and depending on the fault, it can have possible drivability complaints like rough running, hesitation, or reduced power. The broad areas to keep in mind are possible intake air leaks, PCV or vacuum leaks, engine sealing leaks, crankcase pressure sensor circuit issues, the crankcase pressure sensor itself, and in some cases PCM involvement. Start with the basic system checks. If P0068 is present with other fault codes, check what those codes mean first so you are not chasing a rationality code caused by another fault.

If the complaint is PCV-related symptoms without the target code

There is also a shared symptom path in this PCV routine. If the concern is a crankcase ventilation symptom without the listed codes, visually inspect the PCV valve, hoses, and connections for damage, leaks, or restrictions. Check the crankcase for missing, damaged, or leaking gaskets, seals, or other engine sealing components. Make sure the PCV valve maintenance has been followed, the correct PCV valve part number is being used when that information is available, the PCV valve is clean, and the fresh air tube and related hoses are clean and routed correctly. If you find a concern, repair it as necessary and verify the symptom is gone. If you do not find a concern, continue to the PCV system check later in the routine.

Check for air, vacuum, and PCV system leaks first

For P0068, the first real move is a careful leak inspection. Look for disconnected, damaged, or restricted vacuum lines, intake air system lines, and PCV system lines. Check the crankcase sealing areas for missing, damaged, or leaking gaskets, seals, or engine sealing components. Pay attention to the PCV hose O-ring, the oil level indicator and its O-ring, the oil cap, valve cover sealing, and any air leak between the throttle body and the intake valves. Also check that the throttle plate is not sticking or binding, and confirm the correct PCV valve part number. If you find a problem here, repair it as necessary, clear the PCM DTCs, and repeat the self-test. If no concern is found, continue into the crankcase pressure PID check.

Use the crankcase pressure PID to split the path

Start the engine and monitor the PCM PID CRNKCAS_P_V in volts. If the voltage is between 3.3 V - 4.3 V, the path moves toward an intermittent harness or connection concern. If the voltage is not between 3.3 V - 4.3 V, move into the crankcase pressure sensor circuit checks.

Check the crankcase pressure sensor circuits

Before probing these circuit checks on the truck in front of you, make sure the connector and lead information clearly matches the application. If the lead information is not clear, stop and verify the diagnostic path before testing. Do not guess at an unstated meter lead. With the ignition off, disconnect the crankcase pressure sensor connector. Turn the ignition on and check voltage between C1546 Pin 3 and C1546 Pin 2. If it is between 4.5 to 5.5V, continue. If it is not in that range, leave this path and diagnose that supply or reference issue first. Next, with the ignition off, disconnect the PCM connector and check resistance between C1546 Pin 1 and C175E Pin 30. If resistance is less than 5 Ω, continue. If it is not, repair the open circuit, clear the PCM DTCs, and repeat the self-test. Then check for a short to ground on the same signal circuit using the correct verified reference lead. The expected result is greater than 10000 Ω. If it is not greater than 10000 Ω, repair the short circuit, clear the PCM DTCs, and repeat the self-test. Finally, check for a short to voltage. With the ignition on, any voltage present means repair the short circuit, clear the PCM DTCs, and repeat the self-test. If no voltage is present, the path for P0068 calls for a new crankcase pressure sensor, then clear the PCM DTCs and repeat the self-test.

If the PID is in range, look for an intermittent

If the crankcase pressure PID was in range, reconnect the crankcase pressure sensor connector and the PCM connector. Start the engine, monitor CRNKCAS_P_V again, and wiggle the harness from the component back to the PCM. If you see a sudden voltage change while watching the PID, repair the concern as necessary, clear the PCM DTCs, and repeat the self-test. If the voltage does not change and the concern cannot be duplicated, pause, recheck the earlier diagnostic path, and avoid guessing.

PCV system check when the routine sends you there

When the routine calls for the PCV system check, start the engine and bring it to normal operating temperature. Disconnect the intake air system crankcase ventilation hose from the air cleaner outlet, then connect a vacuum gauge to that hose and check whether any vacuum is present. Do not leave the gauge connected too long; disconnect the vacuum gauge after 20 seconds or when 30.00 kpa (9 in-Hg) vacuum is reached to avoid component damage. If vacuum is present on the P0068 side of this routine, the PCV system checks OK and you should move away from PCV system faults. If no vacuum is present, check for vacuum leaks or restrictions in the PCV system, including the oil cap, PCV valve, hoses, cut grommets, valve cover bolt torque, or gasket leaks, and repair as necessary.

Verify the repair

Keep verification separate from testing. After any repair in this path, clear the PCM DTCs, repeat the self-test, and confirm P0068 stays gone. The takeaway is simple: prove the air and PCV system are sealed first, then use the crankcase pressure PID and circuit checks to decide whether you have a wiring issue, an intermittent connection, a PCV system issue, or a sensor call. For more diagnostic training, visit stepdiagnostics.com.