P0068: P0068 Diagnostic Guide

What this code means

P0068 may mean the PCM sees throttle position and airflow or manifold pressure information that does not agree with expected engine load.

What the vehicle may do

The vehicle may turn on the check engine light.
The engine can sometimes hesitate, idle roughly, or feel down on power.
The concern may be intermittent if a harness or connection issue is involved.

Possible fault areas

Possible intake air leaks or restrictions
Possible PCV system leaks, restrictions, or sealing concerns
Possible throttle plate sticking or binding
Possible crankcase pressure sensor or circuit concerns

Diagnostic path

Opening and code logic

On this 2015 to 2025 F-150 with the 3.5 EcoBoost, P0068 means the PCM may be seeing an airflow and load calculation that does not line up. In plain terms, it is comparing throttle position against airflow or manifold pressure information, and the readings are not consistent with the calibrated load values. The truck may have a check engine light, and it can have possible drivability complaints like hesitation, rough running, or reduced power, depending on the fault. The broad areas to keep in mind are possible intake air leaks, PCV system leaks or restrictions, throttle plate sticking, and crankcase pressure sensor or circuit concerns. Start by checking which codes are present. If P0068 is present along with this PCV and air-leak code family, move into the leak checks. If other codes are present, check what they mean first so you do not get pulled into the wrong path.

Symptom-only PCV visual check

Before the P0068 path, this shared test also has a symptom-only branch. If there are PCV-type symptoms but no codes, do a visual inspection of the PCV system. Check 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 parts. Make sure the PCV valve maintenance has been kept up, verify the correct PCV valve part number when available, make sure the valve is clean, and make sure 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 that visual check is clean, continue to the PCV system vacuum check later in the test.

Start the P0068 path with leaks and obvious air path faults

With P0068 present, start by checking for leaks and restrictions in the air and crankcase ventilation paths. Look for disconnected, damaged, or restricted vacuum lines, intake air system lines, and PCV system lines. Check crankcase sealing points for missing, damaged, or leaking gaskets, seals, or engine sealing components. Also look at the PCV hose o-ring seal, the oil level indicator and its o-ring seal, the oil cap, valve cover sealing, and any air leaks between the throttle body and intake valves. While you are there, make sure the intake throttle plate is not sticking or binding, and verify the correct PCV valve part number. If you find a concern, repair it as necessary, clear the PCM DTCs, and repeat the self-test. If no concern is found, stay on the P0068 path and move into the crankcase pressure sensor signal checks.

Monitor the crankcase pressure sensor PID

Start the engine and monitor the PCM CRNKCAS_P_V PID. The expected voltage window here is 3.3 V - 4.3 V. If the PID is inside that range, go straight to the intermittent concern check. If it is outside that range, shut the engine down and start checking the sensor circuit directly.

Check sensor voltage supply

With the ignition off, disconnect the crankcase pressure sensor connector. Turn the ignition on and measure voltage between C1546 Pin 3 and C1546 Pin 2. The voltage should be between 4.5 to 5.5V. If that voltage is correct, continue with the signal circuit checks. If it is not in that range, stop this path and handle that circuit fault before continuing; do not guess past a missing or incorrect sensor supply.

Check the signal circuit for open, short to ground, and short to voltage

Next, turn the ignition off, disconnect the PCM connector, and check the signal circuit. Measure resistance between C1546 Pin 1 and C175E Pin 30. It should be less than 5 Ω. If it is not, repair the open circuit, clear the PCM DTCs, and repeat the self-test. If the circuit passes, check for a short to ground by measuring between C1546 Pin 1 and ground. That reading should be greater than 10000 Ω. If it is not, repair the short circuit, clear the PCM DTCs, and repeat the self-test. If that passes too, turn the ignition on and check for voltage between C1546 Pin 1 and ground. If any voltage is present, repair the short circuit, clear the PCM DTCs, and repeat the self-test. If no voltage is present, then for P0068, install a new Crankcase Pressure sensor, clear the PCM DTCs, and repeat the self-test.

Check for an intermittent signal concern

If the crankcase pressure sensor PID was in range, or after the circuit path brings you to an intermittent check, turn the ignition off and reconnect the crankcase pressure sensor connector and the PCM connector. Start the engine, monitor the CRNKCAS_P_V PID, and wiggle the harness from the component back to the PCM. If the voltage suddenly changes while you are moving the harness, repair the concern as necessary, clear the PCM DTCs, and repeat the self-test. If there is no sudden change, the concern cannot be duplicated or identified at that moment. Pause, recheck the earlier diagnostic path, and avoid guessing before moving into intermittent diagnostics.

PCV system vacuum check

The last shared branch is the PCV system check. Start the engine and let it reach 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. Use the gauge carefully: disconnect the vacuum gauge after 20 seconds or 30.00 kpa (9 in-Hg) vacuum is reached to avoid component damage. If vacuum is present and you are on the P0068 side of the test, the PCV system checks OK and you need to continue diagnosis based on the symptom path. 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 a gasket leak, and repair as necessary.

Verify and close

After any repair, clear the PCM DTCs and repeat the self-test. Keep verification separate from testing: first prove the air path, then prove the crankcase pressure sensor circuit, then confirm the code stays gone. The takeaway on P0068 is simple: do not condemn the sensor until the leak checks and circuit checks support it. For more diagnostic training, visit stepdiagnostics.com.