OBD-II Diagnostic Trouble Code
P0747 — Pressure Control Solenoid A Stuck On
P0747 indicates pressure control solenoid A appears stuck on, meaning pressure stays at a level the TCM did not command.
Severity 4/5
Truck-relevant
Stop within 50 mi
Severity
Stop within 50 mi
Pressure Control Solenoid A Stuck On
Code
P0747
Category
Powertrain
Subsystem
Transmission
Truck-relevant
Yes
What this means for truckers
P0747 (Pressure Control Solenoid A Stuck On) — main line pressure can't drop because the PC solenoid is hung up. On HD automatics this causes harsh shifts, no torque converter lockup, and eventually catastrophic line pressure buildup. Fix: replace PC solenoid (usually requires dropping the trans pan, $600-1,400 in shop labor). Don't ignore — running high line pressure shortens transmission life dramatically.
Before you replace parts — try this first
P0747 on the Transmission system is most often stuck pressure control solenoid — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Harsh shifts and firm engagement, or soft shifts, depending on whether the solenoid is normally high or normally low; limp mode and the check-engine light.
Common causes
- CommonStuck pressure control solenoid ($300–$1000)
- OccasionalDebris in valve body ($500–$1500)
- OccasionalContaminated fluid ($100–$600)
How to fix
Check fluid and filter
When to use: First
Pressure test while commanding the solenoid
When to use: When fluid is good
Replace solenoid or service valve body
When to use: When solenoid is stuck
Affects most
- GMC Sierra 35003 complaints mention this code
- Chevrolet Silverado 35002 complaints mention this code
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P0700 — Transmission Control System Malfunction
- → P0701 — Transmission Control System Range/Performance
- → P0702 — Transmission Control System Electrical
- → P0703 — Brake Switch B Circuit
- → P0705 — Transmission Range Sensor Circuit Malfunction
- → Complaints on GMC Sierra 3500
- → Complaints on Chevrolet Silverado 3500
Frequently Asked Questions
Can I drive with code P0747?
Drive with caution. P0747 is severity 4 — stop within ~50 miles. Most commercial diesel codes at this severity (turbo, fuel rail, transmission solenoid) can damage adjacent expensive components if left unrepaired. Get to a service location before highway-speed loads.
How much does it cost to fix P0747 on a commercial truck?
Total repair cost ranges $100–$1500 depending on the root cause. The cheapest fix is usually the first one listed below — Stuck pressure control solenoid — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P0747 fail a DOT inspection?
P0747 typically doesn't fail an inspection on its own. Inspectors focus on safety items (brakes, steering, tires, lights, HOS). Transmission codes only become an issue if the truck has shifting problems severe enough to qualify as 'mechanical fitness' OOS. Fix to prevent escalation.
What's the difference between P0747 and related codes?
P0747 is closely related to: P0700 (Transmission Control System Malfunction), P0701 (Transmission Control System Range/Performance), P0702 (Transmission Control System Electrical), P0703 (Brake Switch B Circuit). These codes share the same subsystem (transmission) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P0747 is set without the companions, the issue is more isolated.
How do I prevent P0747 from coming back after a repair?
For P0747 (Pressure Control Solenoid A Stuck On), prevention centers on the transmission system. Service transmission fluid at the OEM interval (typically 150K–250K miles for HD autos). Don't skip the magnet/strainer inspection. After repair, perform an adaptive shift relearn with a scan tool (or drive 40+ miles for adaptive ECMs to relearn naturally).