P0968 Pressure Control Solenoid "C" Control Circuit/Open

The P0968 trouble code is an OBD-II diagnostic trouble code related to the electronic and hydraulic control system of an automatic transmission.

P0968 – Pressure Control Solenoid “C” Control Circuit/Open

This code means that the transmission control module (TCM) or powertrain control module (PCM) has detected an open or interrupted electrical circuit involving Pressure Control Solenoid “C.”

In simple terms, the transmission computer is attempting to control Pressure Control Solenoid “C,” but it detects that the electrical circuit is broken, disconnected, or not conducting as expected.

The problem may be caused by a failed solenoid, broken wire, disconnected connector, damaged terminal, corrosion, an internal open circuit in the solenoid coil, or, less commonly, a TCM problem.

What Does P0968 Mean?

P0968 – Pressure Control Solenoid “C” Control Circuit/Open

Automatic transmissions use electronically controlled solenoids to regulate hydraulic pressure.

The TCM sends electrical commands to pressure-control solenoids according to operating conditions such as:

• Engine RPM

• Vehicle speed

• Throttle position

• Engine load

• Transmission temperature

• Selected gear

• Torque demand

• Driving conditions

Pressure Control Solenoid “C” regulates hydraulic pressure within a specific transmission circuit.

When the TCM detects that the electrical circuit controlling this solenoid is open or interrupted, it may store P0968.

A simplified operating sequence is:

TCM command → Electrical circuit → Pressure Control Solenoid “C” → Hydraulic pressure → Transmission operation

If the electrical connection between the TCM and solenoid is interrupted, the solenoid may not be able to perform its function.

What Is a Pressure Control Solenoid?

A pressure control solenoid is an electrically operated hydraulic valve.

Its job is to regulate transmission fluid pressure based on commands from the TCM.

Depending on the transmission design, it may influence:

• Main line pressure

• Clutch pressure

• Shift pressure

• Torque converter pressure

• Specific hydraulic circuits

The TCM adjusts solenoid operation continuously to provide the correct hydraulic pressure for different driving conditions.

What Does the “C” Mean?

The “C” identifies a particular pressure-control solenoid according to the manufacturer's transmission design.

It does not necessarily mean that this is the third solenoid physically installed in the transmission.

Different transmissions use different solenoid arrangements.

Pressure Control Solenoid “C” may be located:

• Inside the transmission

• Inside the valve body

• In a mechatronic assembly

• On a transmission control assembly

The exact location and function should always be confirmed using vehicle-specific service information.

What Does “Circuit/Open” Mean?

The word “Open” is important in P0968.

An open circuit means that electrical current cannot flow through the intended circuit properly.

Imagine an electrical circuit as a complete loop.

If a wire is broken, a connector is disconnected or a solenoid coil has an internal break, the electrical path is interrupted.

The TCM may therefore detect that the expected current is missing or substantially different from the expected value.

Possible causes include:

• Broken wire

• Disconnected connector

• Loose terminal

• Corroded connector

• Broken solenoid coil

• Damaged wiring

• Internal circuit failure

• TCM driver problem

Does P0968 Mean Pressure Control Solenoid “C” Is Bad?

Not necessarily.

A failed solenoid is one possible cause, but P0968 specifically points toward an open electrical circuit.

The problem could be located anywhere between the TCM and the solenoid.

For example:

TCM → wiring harness → transmission connector → internal wiring → solenoid

A break at any point can potentially trigger P0968.

Therefore, replacing the solenoid without testing the wiring can lead to unnecessary repairs.

Symptoms of P0968

The symptoms depend on the transmission design and the role of Pressure Control Solenoid “C.”

Possible symptoms include:

• Check Engine Light

• Transmission warning light

• Harsh shifting

• Delayed shifting

• Erratic gear changes

• Transmission slipping

• Increased engine RPM

• Poor acceleration

• Delayed Drive engagement

• Delayed Reverse engagement

• Transmission stuck in one gear

• Limp mode

• Reduced fuel economy

Some vehicles may continue to drive relatively normally despite storing P0968.

In those cases, the Check Engine Light may be the only noticeable symptom.

Common Causes of P0968

Several electrical problems can trigger this code.

Broken or disconnected wiring

A broken wire is one of the most straightforward causes of an open-circuit code.

Transmission wiring is exposed to:

• Heat

• Vibration

• Moisture

• Transmission fluid

• Oil

• Road contamination

Over time, the harness can become damaged.

Possible problems include:

• Broken conductor

• Chafed wire

• Melted insulation

• Pinched wiring

• Corrosion

• Poor previous repairs

Disconnected transmission connector

If the transmission connector is not properly connected, the TCM may lose electrical communication with the solenoid.

This can happen after:

• Transmission repair

• Valve-body work

• Fluid service

• Harness replacement

• Transmission replacement

Loose or damaged terminals

A connector may appear connected while one terminal has insufficient contact.

Possible problems include:

• Loose terminal

• Bent pin

• Backed-out terminal

• Corrosion

• Damaged locking mechanism

Faulty Pressure Control Solenoid “C”

The solenoid itself can develop an internal open circuit.

For example, the internal coil winding can break.

In this situation, the external wiring may be completely intact while the solenoid cannot conduct current.

Corrosion

Moisture and transmission-fluid contamination can cause corrosion inside connectors and terminals.

Corrosion increases electrical resistance and can eventually interrupt the circuit.

Internal transmission wiring problem

Some transmissions contain internal wiring harnesses that connect the external transmission connector to the solenoids.

Damage to this internal harness can produce an open circuit.

TCM fault

The TCM controls the solenoid circuit electronically.

A failed TCM driver could potentially cause an abnormal circuit condition.

However, the TCM should generally be considered only after the wiring, connectors and solenoid have been tested.

Can Low Transmission Fluid Cause P0968?

Low transmission fluid does not normally cause P0968 directly.

P0968 is primarily an electrical circuit/open code.

Low fluid can cause:

• Slipping

• Delayed engagement

• Poor shifting

• Low hydraulic pressure

But it normally cannot physically create an open electrical circuit.

The transmission fluid level should still be checked because low fluid may cause separate transmission problems.

Can Dirty Transmission Fluid Cause P0968?

Dirty transmission fluid can contribute to solenoid and valve-body problems.

It may cause:

• Solenoid sticking

• Valve sticking

• Restricted passages

• Poor pressure control

However, contaminated fluid does not normally create an open electrical circuit.

If P0968 is present, the electrical circuit should be inspected first.

P0968 vs. P0969 vs. P0970 vs. P0971

These codes are closely related but describe different conditions.

P0968 – Pressure Control Solenoid “C” Control Circuit/Open

The control circuit is open or interrupted.

P0969 – Pressure Control Solenoid “C” Control Circuit Range/Performance

The solenoid circuit or its operation is outside the expected range.

P0970 – Pressure Control Solenoid “C” Control Circuit Low

The TCM detects an electrical condition lower than expected.

P0971 – Pressure Control Solenoid “C” Control Circuit High

The TCM detects an electrical condition higher than expected.

The distinction is useful during diagnosis because P0968 should strongly direct attention toward continuity, wiring, connectors and the solenoid coil.

How Serious Is P0968?

P0968 can be relatively simple or potentially serious.

A broken wire or loose connector may be repaired without opening the transmission.

However, if Pressure Control Solenoid “C” controls an important hydraulic circuit, its failure can significantly affect transmission operation.

Possible consequences include:

• Harsh shifts

• Incorrect clutch pressure

• Transmission slipping

• Excessive heat

• Limp mode

• Accelerated internal wear

For this reason, P0968 should not be ignored.

Can You Drive With P0968?

If the vehicle shifts normally and there are no severe symptoms, a short drive to a repair facility may be possible.

However, prolonged driving is not recommended until the electrical fault has been diagnosed.

Driving should be minimized if you experience:

• Severe transmission slipping

• Violent shifting

• Loss of Drive

• Loss of Reverse

• Transmission overheating

• Limp mode

• Burning transmission fluid smell

These symptoms can indicate that the transmission is not being controlled correctly.

How to Diagnose P0968

Because P0968 indicates an open circuit, the diagnostic process should concentrate heavily on the electrical path between the TCM and Pressure Control Solenoid “C.”

1. Scan the TCM

Use a professional diagnostic scanner to retrieve all stored and pending codes.

Check for additional codes involving:

• Other pressure-control solenoids

• Shift solenoids

• Transmission pressure sensors

• Transmission temperature

• Gear ratios

• Power supply

• Communication

If several solenoids have circuit faults at the same time, a shared wiring or power-supply problem becomes more likely.

2. Check freeze-frame data

Review the conditions under which P0968 was stored.

Useful information may include:

• Engine RPM

• Vehicle speed

• Transmission temperature

• Selected gear

• Throttle position

• Transmission operating mode

This can help determine whether the fault is permanent or intermittent.

3. Identify Pressure Control Solenoid “C”

Use the manufacturer's wiring diagram to identify:

• Solenoid location

• Connector pinout

• TCM terminals

• Power supply

• Control wire

• Internal transmission wiring

Do not assume that the solenoid layout is the same between different transmissions.

4. Inspect the external wiring

Carefully inspect the harness between the TCM and transmission.

Look for:

• Broken wires

• Chafing

• Melted insulation

• Pinched wires

• Corrosion

• Poor repairs

• Damaged harness clips

Pay special attention to areas exposed to heat or movement.

5. Inspect the transmission connector

Check for:

• Loose terminals

• Bent pins

• Corrosion

• Water intrusion

• Transmission fluid contamination

• Backed-out terminals

• Damaged connector locks

A connector that appears properly installed can still have a terminal that has moved backward inside the housing.

6. Check circuit continuity

With the appropriate connectors disconnected, check continuity between the relevant TCM terminal and the solenoid circuit.

A properly functioning circuit should have continuity within the manufacturer's specification.

An open reading indicates a possible:

• Broken wire

• Disconnected terminal

• Internal harness problem

• Connector problem

Always follow the manufacturer's testing procedure.

7. Measure solenoid resistance

Measure the resistance of Pressure Control Solenoid “C.”

Compare the result with the manufacturer's specification.

If the meter indicates OL/open circuit where a measurable resistance should exist, the solenoid coil may be internally open.

Do not assume that every transmission uses the same resistance value.

8. Check the circuit for unwanted resistance

A wire may not be completely broken but can have excessive resistance because of:

• Corrosion

• Damaged conductor strands

• Poor terminal contact

• Previous poor-quality repairs

Voltage-drop testing can be useful in identifying these problems.

9. Check internal transmission wiring

If the external harness and connector are good, the internal transmission harness may need to be inspected.

This can require access to the transmission pan or valve-body area, depending on the transmission design.

10. Check the TCM circuit

If the solenoid and wiring are confirmed to be good, the TCM output circuit can be tested according to the manufacturer's procedure.

A TCM failure should generally be diagnosed only after other possible causes have been eliminated.

Why P0968 Can Be Difficult to Diagnose

A circuit that is open continuously is usually easier to find.

However, an intermittent open circuit can be much more difficult.

The fault may appear only when:

• The transmission is hot

• The vehicle is moving

• The harness vibrates

• The engine or transmission moves under load

• A connector expands with temperature

• The vehicle encounters bumps

A wire can therefore test correctly when the vehicle is stationary but fail during a road test.

P0968 After Transmission Repair

If P0968 appeared immediately after transmission repair or replacement, the repair area should be inspected first.

Possible causes include:

• Connector not fully seated

• Bent connector terminal

• Pinched harness

• Disconnected internal wiring

• Damaged solenoid connector

• Incorrect harness routing

• Damaged wiring during transmission removal

A code appearing immediately after transmission work does not automatically mean that the transmission itself has failed.

P0968 After a Transmission Fluid Change

A fluid change does not normally cause an electrical open-circuit code.

However, if P0968 appeared immediately after transmission service, inspect:

• Transmission connector

• Wiring harness

• Solenoid connections

• Internal harness

• Fluid contamination around electrical connectors

If the transmission pan or valve body was removed during the service, the internal wiring and solenoid connections deserve particular attention.

Can P0968 Cause Limp Mode?

Yes.

Depending on the transmission design, the TCM may activate a protective operating strategy when it detects that Pressure Control Solenoid “C” cannot be controlled.

The vehicle may:

• Remain in a particular gear

• Use a limited number of gears

• Shift harshly

• Increase line pressure

• Delay engagement

• Restrict transmission operation

Not every vehicle with P0968 will enter limp mode.

The exact response depends on the transmission and control software.

Can P0968 Damage the Transmission?

P0968 does not automatically mean that internal transmission damage has occurred.

However, if the missing solenoid control causes incorrect hydraulic pressure or clutch engagement, continued operation can increase:

• Clutch wear

• Heat

• Hydraulic stress

• Internal component wear

If the transmission is slipping or shifting violently, continued driving should be avoided.

Common Diagnostic Mistakes With P0968

One of the biggest mistakes is immediately replacing Pressure Control Solenoid “C.”

An open circuit may be caused by a broken wire or connector rather than the solenoid.

Another common mistake is checking only the external wiring.

Some transmissions have internal wiring harnesses that can fail.

Another mistake is assuming that a connector is good simply because it looks connected.

A terminal can be loose, corroded or pushed backward inside the connector.

Replacing the TCM too early is another mistake.

P0968 does not automatically mean that the TCM is defective.

The wiring, connectors and solenoid should be tested first.

What Is the Correct Repair for P0968?

The correct repair depends on where the open circuit is found.

Possible repairs include:

• Replacing Pressure Control Solenoid “C”

• Repairing a broken wire

• Replacing damaged wiring

• Repairing a loose terminal

• Replacing a damaged connector

• Removing corrosion

• Repairing internal transmission wiring

• Correcting connector installation

• Repairing the solenoid control circuit

• Repairing or replacing the TCM when conclusively diagnosed as faulty

After the repair, the diagnostic codes should be cleared and the vehicle should be tested under the conditions in which the fault originally occurred.

Final Thoughts on P0968

P0968 – Pressure Control Solenoid “C” Control Circuit/Open indicates that the transmission control module has detected an open or interrupted electrical circuit involving Pressure Control Solenoid “C.”

Unlike P0969, which describes a range/performance problem, P0968 points more specifically toward an interruption in the electrical circuit.

The most important areas to inspect are the wiring harness, connectors, terminals, internal transmission wiring and Pressure Control Solenoid “C” itself.

Low transmission fluid or dirty fluid may cause separate transmission problems, but they do not normally create an electrical open circuit.

A proper diagnosis should begin by identifying the correct solenoid and wiring circuit, inspecting the connectors and harness, checking continuity and measuring solenoid resistance. If these components are confirmed to be functioning correctly, the TCM control circuit can then be investigated.

P0968 does not automatically mean that the transmission needs to be rebuilt or replaced. Finding the exact point where the electrical circuit is interrupted can often prevent unnecessary transmission repairs and parts replacement.