P0799 — Pressure Control Solenoid “C” Intermittent #
Note: The wording for this code may vary depending on the manufacturer.
- Pressure Control Solenoid “C” Intermittent (Generic / Most OEMs)
- Shift Solenoid C Intermittent Fault (Honda/Acura)
- Shift Solenoid Valve C Range/Performance Intermittent (Toyota/Lexus)
- Transmission Pressure Control Solenoid C Intermittent (Ford/GM/Chrysler)
Code Summary for P0799 #
P0799 is a diagnostic trouble code (DTC) that indicates an intermittent electrical or hydraulic issue with the Pressure Control Solenoid “C” in your vehicle’s automatic transmission. The Pressure Control Solenoid is an electro-hydraulic valve that regulates fluid pressure to control gear shifts smoothly. When the Powertrain Control Module (PCM) or Transmission Control Module (TCM) detects inconsistent signals or operation from solenoid “C”, it sets this code. An intermittent code means the fault appears and disappears, making it potentially tricky to pinpoint. This condition may cause shifting problems, transmission warning lights, or erratic transmission behavior.
Common Symptoms for Code P0799 #
When P0799 is stored, you might experience a range of transmission-related symptoms. These can be subtle or pronounced, depending on how often the solenoid “C” malfunctions. If you notice any of the following, your transmission may be trying to tell you something:
- Erratic or harsh shifting between gears
- Transmission slipping or failing to engage gears
- Delayed gear engagement (especially when accelerating from a stop)
- Transmission stuck in limp mode (limited gear operation to protect the system)
- Check Engine Light or Transmission Warning Light illuminated
- Occasional jerking or surging at low or moderate speeds
Probable Causes for DTC P0799 (Most to Least Common) #
Several factors can lead to the P0799 code, ranging from electrical glitches to mechanical wear. It’s critical to address the most common causes first to save time and money:
- Faulty Pressure Control Solenoid “C” (internal electrical or mechanical failure)
- Intermittent wiring/connectors issues (corroded, loose, or damaged harness at solenoid or TCM/PCM)
- Low, dirty, or contaminated transmission fluid
- Internal hydraulic blockage (debris in valve body or solenoid passages)
- Faulty Transmission Control Module (TCM) or PCM (rare)
- Shorts or opens in the circuit (less frequent but possible)
Step-by-Step Diagnostic for P0799 #
To accurately diagnose P0799, a methodical approach is essential. Even seasoned technicians know that intermittent faults require patience and attention to detail. Here’s a proven workflow:
- Verify the code with a professional OBD-II scanner; note any related transmission codes.
- Check transmission fluid level and condition: Top up or replace if low, dirty, or burnt.
- Inspect wiring and connectors at the pressure control solenoid “C” and the TCM/PCM for corrosion, damage, or looseness.
- Perform a wiggle test on the harness while monitoring live data for dropouts or erratic readings.
- Test the solenoid “C” resistance and operation using a multimeter and, if possible, actuator tests via scan tool.
- Check for internal blockages or debris in the valve body (requires pan removal and visual inspection).
- Test TCM/PCM outputs if all other steps are inconclusive (usually a last resort).
Possible Repairs for Code P0799 #
Depending on the results of your diagnostics, the following repairs can resolve P0799. Always address the root cause to avoid repeat failures:
- Replace Pressure Control Solenoid “C” (most common fix)
- Repair or replace damaged wiring/connectors as needed
- Flush and replace transmission fluid and filter
- Clean or repair valve body if debris or blockage is found
- Replace or reprogram TCM/PCM if verified faulty (rare)
- Clear code and road test to verify proper operation
Is It Safe to Drive With Code P0799? #
Limited. While your vehicle may still move, P0799 can cause unpredictable shifting, limp mode, or complete loss of drive. Continuing to drive with this code risks further transmission damage and potential safety issues, especially if the vehicle suddenly loses power or fails to shift. If you notice severe symptoms or the transmission is stuck in one gear, stop driving and seek professional repair immediately. For minor symptoms, short trips to a repair facility may be acceptable, but delay is not recommended.
Vehicles Most Commonly Affected by P0799 #
This code can appear on any OBD-II equipped vehicle with electronically controlled automatic transmissions, but some platforms are more frequently reported:
- Honda/Acura vehicles (especially 2000s–2010s Accord, Odyssey, Civic)
- Toyota/Lexus (Camry, RAV4, ES/GS series with U-series automatics)
- GM (Chevrolet Malibu, Impala, Silverado, GMC Sierra)
- Ford (Fusion, Escape, F-150 with 6-speed automatics)
- Chrysler/Dodge/Jeep (minivans, SUVs with 42RLE or 62TE transmissions)
Common Mistakes & Best Practices with P0799 #
Even experienced technicians can overlook key steps or jump to conclusions. Avoid these pitfalls for a smooth repair:
- Replacing the solenoid without checking the wiring or fluid condition first
- Ignoring intermittent wiring issues (most common root cause)
- Using the wrong transmission fluid type (always use OEM-recommended)
- Not clearing codes and confirming repair with a road test
- Forgetting to inspect for valve body debris or contamination
Quick FAQ for P0799 #
Q: Can a bad battery or alternator cause P0799?
A: Rarely. Electrical supply issues can occasionally trigger or worsen intermittent solenoid codes, but P0799 is most often due to wiring, fluid, or solenoid faults.
Q: Will a transmission fluid change fix P0799?
A: Only if the issue is due to low, dirty, or contaminated fluid. If the solenoid or wiring is faulty, fluid service alone won’t resolve the problem.
Q: Do I need to remove the transmission to replace the solenoid?
A: Usually not. On most vehicles, the solenoids are accessible by removing the transmission oil pan and valve body. Always consult your service manual for specific procedures.
