OBD-II trouble code
P0798: Pressure Control Solenoid "C" Electrical
The transmission control module has detected an electrical fault in the circuit for pressure control solenoid C — an open, short, or out-of-range resistance. Expect shift-quality problems and possibly limp mode.
Quick facts
- System
- Powertrain
- Category
- Transmission / Pressure Control
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $150 – $800
- DIY difficulty
- Shop recommended
One of 26 pressure control solenoid codes
P0798 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 26 and explains how to read them against each other.
See all pressure control solenoid codes →Browse every code in P0700–P0799, or start from the full code library.
What does P0798 mean?
P0798 is the electrical-fault code for pressure control solenoid "C." It sets when the transmission control module (TCM) or PCM detects the solenoid's electrical circuit outside its normal range — an open, a short to power or ground, or resistance that doesn't match specification. It's the electrical sibling of the solenoid's performance codes: rather than describing how the solenoid behaves hydraulically, P0798 reports that the module can't electrically drive the solenoid or is reading an unexpected current.
Pressure control solenoid C is another of the transmission's variable-force pressure solenoids. Modern transmissions use several of these to regulate line and clutch-apply pressure across the gear range, and each has its own letter designation. When the circuit for solenoid C faults, the module loses accurate control of the pressure that solenoid manages, producing harsh, delayed, or wrong shifts, and often triggering a limp or failsafe mode that locks the transmission in one gear to protect it.
As with the other pressure-control electrical codes, the causes are electrical first: a corroded or damaged transmission connector, chafed or broken harness wiring, a failed solenoid coil, or an internal case-harness problem. Diagnosis begins with the connector, the wiring, and a resistance check of the solenoid — not a fluid change — though contaminated fluid can shorten solenoid life and is worth noting. Because several solenoids share the transmission connector, it's important to confirm the letter designation for your specific transmission, since which physical solenoid is "C" varies between designs.
Common causes
- Corroded, loose, or damaged transmission connector
- Chafed, broken, or shorted wiring in the solenoid C circuit
- Failed pressure control solenoid C coil (open or shorted)
- Damaged internal transmission wiring harness or pass-through connector
- Poor ground or voltage supply to the transmission control circuit
- Contaminated fluid that has degraded the solenoid over time
Symptoms
- Check engine light on with P0798 stored
- Harsh, delayed, or erratic shifts
- Transmission stuck in a single gear (limp mode)
- Slipping or flaring between shifts
- Transmission running warm
- Reduced fuel economy
Diagnostic steps
- 1.Scan for all transmission codes; a stored P0700 confirms the TCM has logged faults and provides freeze-frame data.
- 2.Inspect the transmission connector and external harness for corrosion, damage, and backed-out pins.
- 3.Resistance-check pressure control solenoid C against the manufacturer's spec — an open or shorted reading confirms an electrical fault.
- 4.Check for continuity and shorts to power or ground along the solenoid wiring back to the module.
- 5.Verify the module's power and ground supplies are solid before condemning the solenoid.
- 6.If the external circuit is good but the solenoid reads out of spec, the solenoid or internal harness is the likely fault.
Repair cost
$150 – $800
An external wiring or connector repair can run $100-$300. Replacing pressure control solenoid C is typically $250-$700 depending on access to the pan and valve body. An internal case-harness fault raises labor. Spend the diagnostic time to isolate whether the fault is external wiring or the solenoid itself before ordering parts.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with transmission shift solenoid replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
Leave this one to a qualified shop. The barrier here is internal hydraulic and mechanical work, fluid handling at temperature, and an adaptive relearn afterwards without which a correct repair still shifts badly. DIY attempts often produce a more expensive problem than the original code.