P0780

Pressure Control Solenoid B Performance

Powertrain Transmission Control Pressure Control 🟡 Moderate — Fix within a week ⚠️ Drive with Care
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What This Actually Means

In plain language — no jargon

The transmission's pressure control solenoid B isn't working properly, causing incorrect fluid pressure in your gears. It's like a faulty valve in your plumbing that can't maintain steady water pressure.

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Symptoms You May Notice

3 known symptoms for this code
Transmission slipping or delayed gear engagement
Harsh or erratic shifting between gears
Transmission overheating or limp mode activation
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECM monitors solenoid B's ability to modulate transmission fluid pressure by measuring electrical current draw and feedback from pressure sensors. The solenoid receives a PWM signal to regulate pressure; if actual pressure doesn't match commanded pressure within the expected range, a fault is triggered.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Solenoid B Current Draw 0.5-2.5 amps at command <0.2 amps or >3.0 amps
Measured Fluid Pressure vs Command Within 5-10 PSI of target Deviation >20 PSI or no response
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Transmission fluid and filter
Change fluid and filter to remove debris clogging the solenoid valve.
2
Solenoid B connector and wiring
Inspect connector for corrosion, clean terminals, and check for loose or damaged wires.
3
Pressure Control Solenoid B
Replace the solenoid if electrical and fluid checks pass.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P0780 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code P0780

What happens after you fix the fault

Once the fault is repaired, P0780 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.