P0779 — Pressure Control Solenoid B Intermittent

OBD2 code P0779 flags a problem with the automatic transmission control (pressure control solenoid b intermittent). Short, gentle driving to a shop is usually possible. Common culprits: low or degraded transmission fluid, internal mechanical wear (clutches, torque converter), wiring or connector faults in the valve body harness.

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive only if the transmission still shifts predictably, and avoid highway speeds. Driving with slipping or limp mode accelerates internal wear — every kilometre can add to the final repair bill.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0779 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the automatic transmission control for damage, corrosion, chafing or poor contact.
Subsystem check Check transmission fluid level and condition — dark, burnt fluid points to internal wear.
Subsystem check Read transmission-specific codes and live data (solenoid states, input/output speed) with a capable scanner.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0779 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0779 (parts and labor, USD, independent shop rates): Replace a shift solenoid: $300–$800; Transmission rebuild or replacement: $2,500–$5,500; Valve body repair or replacement: $700–$1,500; Transmission fluid service: $150–$350. Overall, fixing P0779 usually costs between $150 and $5,500. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What does OBD2 code P0779 mean?

Is it safe to drive with P0779?

Drive only if the transmission still shifts predictably, and avoid highway speeds. Driving with slipping or limp mode accelerates internal wear — every kilometre can add to the final repair bill.

What are the symptoms of P0779?

Drivers most often notice: shuddering at highway speed, no movement in severe cases, harsh or delayed shifting, transmission stuck in one gear (limp mode).

What is the most common cause of P0779?

The most common causes are: low or degraded transmission fluid, internal mechanical wear (clutches, torque converter), wiring or connector faults in the valve body harness.

How do I diagnose P0779 myself?

Start with a scan: confirm P0779, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the automatic transmission control, and verify the suspect component against live data before buying parts.

When your vehicle's computer detects an irregular signal coming from the transmission's hydraulic control system, it logs code P0779. The full technical name is "Pressure Control Solenoid B Intermittent," which tells you two things: the problem involves solenoid B (one of several pressure control valves inside the transmission), and the fault is not constant—it comes and goes. P0779 falls under the powertrain category, meaning it affects the engine and transmission working together.

The transmission control module (TCM) or powertrain control module (PCM) constantly monitors how each solenoid performs. Solenoid B specifically manages line pressure and shift quality. For the module to set P0779, it must detect the abnormal signal multiple times under the same driving conditions—your engine is not malfunctioning, but the transmission's hydraulic response is inconsistent. When the code triggers, the module also saves a freeze frame: a snapshot of engine load, RPM, coolant temperature, and vehicle speed at that exact moment. This data pinpoints the scenario where the fault appears, which is crucial for reproducing the issue during diagnosis.

Common Symptoms of P0779

When P0779 is active, you will likely notice changes in how your transmission behaves. The most frequent complaints include:

A shudder or vibration felt at highway cruising speeds
Complete loss of forward or reverse movement in severe cases
Shifts that feel harsh, jerky, or uncharacteristically late
Transmission refusing to leave a single gear (commonly called limp mode)
Engine revving without corresponding acceleration as gears slip

What Causes P0779?

Several issues can trigger P0779, ranging from simple fluid problems to major internal damage. The most likely culprits, ordered from most to least probable, are:

Low or contaminated transmission fluid—often the cheapest fix and most common cause
Worn or sticking valve body components—affects hydraulic pressure regulation
Faulty transmission speed sensor—sends incorrect data to the control module
Internal mechanical wear inside the transmission, including clutch plates and torque converter issues—usually the most expensive to repair

How to Diagnose P0779

Effective diagnosis follows a logical order, starting with the least invasive checks:

Connect an OBD2 scanner, retrieve P0779, and record all freeze frame data—this tells you what engine conditions coincided with the fault.
Scan for additional transmission codes and check manufacturer TSBs for known fixes specific to your vehicle make and model.
Inspect the wiring harness and connectors feeding the transmission control circuit for damage, corrosion, or loose connections.
Measure fluid level and examine its condition—dark, burnt-smelling fluid suggests internal problems beyond a simple service.
Access transmission-specific data with a professional scanner: solenoid operation states, input and output shaft speeds, and commanded line pressure.
Clear the code, drive through conditions matching the freeze frame, and verify P0779 does not reappear.

Repair Options and Costs

Fixing P0779 depends entirely on what component fails. Here are the typical repair scenarios with parts and labor included (USD, independent shop pricing):

Transmission fluid service (drain, fill, and filter): $150–$350
Shift solenoid replacement: $300–$800
Valve body repair or replacement: $700–$1,500
Full transmission rebuild or replacement: $2,500–$5,500

How Much Does It Cost to Fix P0779?

The full range for P0779 repairs spans $150 to $5,500 depending on root cause. Always pursue accurate diagnosis before purchasing parts—the majority of cases turn out to be fluid-related or involve a single solenoid, both far cheaper than a full transmission job. An honest shop will work through the low-cost possibilities first rather than immediately quoting a rebuild