I have three different solenoid codes. Do I need a whole new solenoid pack?

Probably not, and that pattern is actually good news. Solenoids in a pack share conductors — typically a common supply with the module switching each ground individually, or the reverse — so a single fault in that shared section reports on every channel that depends on it. Three solenoids do not fail simultaneously; failure is not that coordinated. Test the shared feed and the case connector before anyone quotes for a pack, because if the shared conductor is the fault, a new pack changes nothing.

The code keeps moving to a different solenoid. What does that mean?

It is the clearest possible sign that the fault is not in any individual solenoid. A failing winding produces the same code every time, because it is the same component failing in the same way. A fault that wanders between channels is a shared conductor, a degraded pin in the connector, or a module power and ground problem — something that affects all the channels a little and tips whichever one happens to be closest to the threshold on a given drive.

Is solenoid C the same part on every transmission?

No. The letter is a slot in the generic code list rather than a part name, and which physical valve a transmission calls C is that transmission's own decision — as is which one it calls A or B, so the letter is not safe to assume anywhere in this family. What makes it matter more here is scope: a transmission with three or four shift solenoids has room to give the later letters jobs that are not shift scheduling at all. Look the part up in service data for your exact transmission before ordering, or you may fit a genuine, correct-for-something-else component.

Where should I start if there is only one code?

Then the shared-conductor argument does not apply and you are looking at that channel specifically — its individual conductor from the module, its pin at the case pass-through connector, and the solenoid winding itself. Even so, check module power and ground first, because it costs minutes and rules out the one remaining common cause. After that, identify the physical solenoid from service data and test it at operating temperature rather than cold.

OBD-II trouble code

P0764: Shift Solenoid "C" Intermittent

Solenoid C is dropping out and recovering. Before condemning it, count the codes: solenoids in a pack share a supply and a return, so faults on more than one channel are one shared conductor, not several failing solenoids.

High severityPowertrainTransmission / Shift ControlDrivable short-term

Quick facts

System: Powertrain
Category: Transmission / Shift Control
Severity: High severity
Drivable: Usually safe to drive short-term
Repair cost range: $120 – $850
DIY difficulty: Advanced DIY

One of 42 shift solenoid codes

P0764 sits in a grid: one axis is which solenoid the letter refers to, the other is what went wrong with it. Each cell is a genuinely different fault with its own diagnosis — but codes from the same row or column often appear together, and what a pairing means is usually the fastest way in. The hub page lays out all 42 and explains how to read them against each other.

See all shift solenoid codes →

Browse every code in P0700–P0799, or start from the full code library.

What does P0764 mean?

P0764 is stored when the module briefly loses and regains a valid electrical picture of shift solenoid C. The most valuable thing to establish about this code is not what solenoid C does but how many other solenoid codes are sitting beside it, because that number decides the whole shape of the repair.

Shift solenoids are not wired as fully independent devices. In a solenoid pack they are grouped, and grouped devices share conductors — commonly a single supply feed to the whole assembly, with the module switching each solenoid's ground individually, or the mirror of that arrangement. Whichever way round it is done, some part of every solenoid's circuit is a conductor it does not own. That shared section is a common-cause failure point, and it produces a pattern anybody can read without a wiring diagram in front of them.

The arithmetic is simple. One solenoid code, appearing consistently, points at that channel — its winding, its individual conductor, its pin in the connector. Two or more solenoid codes appearing together, or drifting from one channel to another over successive drives, does not mean several solenoids are failing at once. Failure is not that coordinated. It means the fault is in something they have in common: the shared supply or ground, the case pass-through as a whole, or the module's own power and ground. Reading the pattern this way is the difference between a wiring repair and an unnecessary solenoid pack, and the pattern costs nothing to read.

There is a second thing worth understanding here, and it applies to the whole family rather than only to this letter. The letter in the code is a slot in the generic SAE list, not a part name: which physical valve a transmission calls A, B, C or D is decided by that transmission's designers, so it is not safe to assume for any of them. What makes it bite harder further down the alphabet is scope — a transmission with three or four shift solenoids has room to give the later letters jobs that are not shift scheduling at all. Ordering "a shift solenoid C" from a parts counter without first identifying what your transmission physically calls by that name is a well-established way to fit the wrong component, and it is the reason service data should be consulted before a part number is.

So the sequence here runs in a specific order. Count the codes and decide whether you are chasing one channel or a shared conductor. Then, only if it really is one channel, identify which physical solenoid your transmission designates as C. Testing before doing both of those is how people end up measuring a healthy component and drawing the wrong conclusion from an entirely correct reading.

Common causes

Fault in the supply or ground shared by every solenoid in the pack, reported on one channel
Degraded pin or terminal in the shared feed at the case pass-through connector
Marginal power or ground to the module driving the solenoids
Individual conductor to solenoid C chafed or intermittently open
Solenoid C winding failing internally, which the code pattern will show as a single-channel fault
Wrong solenoid previously fitted after a parts-counter lookup that did not match the transmission
Corrosion in the connector body affecting adjacent pins at the same time

Symptoms

Several different solenoid codes stored together rather than one repeating consistently
The channel reporting a fault changing from one drive to the next
Erratic shift quality with no repeatable pattern
Intermittent limp mode that clears on restart
Codes returning after a solenoid was replaced on a single channel
Check engine light cycling on and off across drive cycles
Transmission behaving normally for long periods between events
Other transmission electrical codes appearing alongside these

Diagnostic steps

1.Count the solenoid codes before testing anything. One channel reporting consistently is a channel fault. Two or more channels, or a fault that moves between channels across drives, is a shared conductor — and no number of solenoids will fix it.
2.Identify the shared architecture in a wiring diagram for your transmission. Most packs are fed a common supply with the module switching each ground, or the reverse. Knowing which arrangement you have tells you exactly which conductor is common to the affected channels.
3.Test the shared conductor first when the pattern points that way. Measure the supply at the pack with the solenoids commanded, and check the return path for voltage drop under load rather than for continuity, which will pass on a connection that is failing.
4.Verify module power and ground before suspecting anything inside the transmission. A module with a marginal ground will report faults on the outputs it cannot control cleanly, and those look exactly like solenoid problems from the scan tool.
5.Only now identify which physical valve your transmission calls solenoid C. The letter is a generic slot rather than a part name on every member of this family, so confirm the designation in service data for your transmission before testing — that is what prevents a correct test being performed on the wrong component.
6.Confirm the fix by clearing all codes and driving several cycles. Watching which codes return, and whether they return together, retests the shared-versus-single question rather than just the component you replaced.

Repair cost

$120 – $850

Diagnosis is $120 to $250, and on this code it earns its price by answering the shared-conductor question before any part is bought. A wiring or connector repair on a shared feed is $150 to $400. An individual solenoid, where the code pattern genuinely points at one channel, is $350 to $600 fitted on transmissions where the pan drops to reach the valve body. A full solenoid pack is $500 to $850. The expensive mistake this page exists to prevent is fitting a pack because three solenoid codes were stored — three codes usually means one shared conductor, and the pack was never the problem.

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Open the Repair Cost Estimator with transmission shift solenoid replacement preselected. Adjust labor rate and vehicle category to fit your situation.

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DIY vs shop

This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.