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Home / DTC / P0799 — Pressure Control Solenoid C Intermittent

P0799 — Pressure Control Solenoid C Intermittent

Detailed page for trouble code P0799.

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22,491specific
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Code

P0799

Generic P — Powertrain

Pressure Control Solenoid C Intermittent

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged, corroded or loose connector for pressure control solenoid C
  • Broken, chafed or shorted wiring in the solenoid circuit
  • Failing or sticking pressure control solenoid C
  • Contaminated transmission fluid or clogged valve body passage
  • Poor ground or low reference voltage to the solenoid
  • Intermittent TCM/PCM driver output or internal controller fault

Symptoms

  • Check Engine or Transmission warning lamp illuminated
  • Erratic or harsh shifting, delayed shifts or slipping
  • Transmission may go into limp/backup mode
  • Intermittent loss of proper line pressure control
  • Multiple transmission-related DTCs may be present

What to check

  • Read freeze-frame and live data with a scan tool; confirm P0799 and note conditions
  • Visually inspect solenoid connector and wiring for corrosion, damage, or looseness
  • Wiggle harness/connectors while monitoring codes and live data to reproduce the intermittent fault
  • Check transmission fluid level and condition (burnt smell, debris)
  • Measure solenoid coil resistance at the connector with connector disconnected
  • Back-probe power and ground at the solenoid while operating to verify steady supply and switching

Signal parameters

  • Solenoid coil resistance: typically low ohms (varies by design) — commonly in the range ~5–50 Ω; consult vehicle spec
  • Supply voltage: nominal battery/ignition voltage (~12 V) on the power feed
  • Control: modulated by PCM/TCM using PWM; duty cycle varies 0–100% to control pressure
  • PWM frequency: commonly in the range ~50–200 Hz (varies by manufacturer)
  • Expected behavior: steady PWM and stable resistance; intermittent open/short or erratic duty indicates fault

Diagnostic algorithm

  1. Retrieve DTCs and freeze-frame data; note operating conditions when fault set (temp, RPM, gear).
  2. Clear codes and road-test to try to reproduce. Monitor live data for pressure, solenoid status, and shifts.
  3. Visually inspect connector and wiring to solenoid C. Repair any corrosion, bent pins, or damage.
  4. With ignition off, disconnect solenoid connector and measure coil resistance; compare to spec. Replace if open or out of range.
  5. With connector connected, back-probe power and ground while operating; confirm steady battery voltage on power feed and good ground.
  6. Use an oscilloscope or quality scan tool to observe PWM control signal at the solenoid while shifting; look for intermittent loss, noise, or unexpected duty changes.
  7. Perform a wiggle test of the harness/connectors while monitoring the circuit to find intermittent wiring faults.
  8. If electrical checks pass, inspect transmission fluid, filter and valve body for contamination or sticking valve that can mimic solenoid issues.
  9. If possible, swap solenoid C with another identical solenoid position (if same part and wiring) to see if code follows the solenoid.
  10. If solenoid and wiring test good but intermittent fault persists, consider TCM/PCM driver failure and follow manufacturer procedures for module testing or replacement.
  11. Safety note: support vehicle securely and be cautious of hot fluids when checking transmission components.

Likely causes

  • Loose or corroded connector at solenoid C
  • Wiring harness damage (chafe, break, or intermittent short)
  • Failing solenoid (intermittent internal contact or coil)
  • Contaminated fluid/valve body restricting solenoid movement
  • Poor ground or intermittent supply voltage from PCM/TCM

Fault status

⚠️ Status
P0799 — Pressure Control Solenoid C Intermittent: intermittent/open/short or erratic signal detected in transmission pressure control solenoid C circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3 hours

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Code

P0799

LAND ROVER P — Powertrain

Control Solenoid intermittent C pressure

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged, corroded or loose connector for pressure control solenoid C
  • Broken, chafed or shorted wiring in the solenoid circuit
  • Failing or sticking pressure control solenoid C
  • Contaminated transmission fluid or clogged valve body passage
  • Poor ground or low reference voltage to the solenoid
  • Intermittent TCM/PCM driver output or internal controller fault

Symptoms

  • Check Engine or Transmission warning lamp illuminated
  • Erratic or harsh shifting, delayed shifts or slipping
  • Transmission may go into limp/backup mode
  • Intermittent loss of proper line pressure control
  • Multiple transmission-related DTCs may be present

What to check

  • Read freeze-frame and live data with a scan tool; confirm P0799 and note conditions
  • Visually inspect solenoid connector and wiring for corrosion, damage, or looseness
  • Wiggle harness/connectors while monitoring codes and live data to reproduce the intermittent fault
  • Check transmission fluid level and condition (burnt smell, debris)
  • Measure solenoid coil resistance at the connector with connector disconnected
  • Back-probe power and ground at the solenoid while operating to verify steady supply and switching

Signal parameters

  • Solenoid coil resistance: typically low ohms (varies by design) — commonly in the range ~5–50 Ω; consult vehicle spec
  • Supply voltage: nominal battery/ignition voltage (~12 V) on the power feed
  • Control: modulated by PCM/TCM using PWM; duty cycle varies 0–100% to control pressure
  • PWM frequency: commonly in the range ~50–200 Hz (varies by manufacturer)
  • Expected behavior: steady PWM and stable resistance; intermittent open/short or erratic duty indicates fault

Diagnostic algorithm

  1. Retrieve DTCs and freeze-frame data; note operating conditions when fault set (temp, RPM, gear).
  2. Clear codes and road-test to try to reproduce. Monitor live data for pressure, solenoid status, and shifts.
  3. Visually inspect connector and wiring to solenoid C. Repair any corrosion, bent pins, or damage.
  4. With ignition off, disconnect solenoid connector and measure coil resistance; compare to spec. Replace if open or out of range.
  5. With connector connected, back-probe power and ground while operating; confirm steady battery voltage on power feed and good ground.
  6. Use an oscilloscope or quality scan tool to observe PWM control signal at the solenoid while shifting; look for intermittent loss, noise, or unexpected duty changes.
  7. Perform a wiggle test of the harness/connectors while monitoring the circuit to find intermittent wiring faults.
  8. If electrical checks pass, inspect transmission fluid, filter and valve body for contamination or sticking valve that can mimic solenoid issues.
  9. If possible, swap solenoid C with another identical solenoid position (if same part and wiring) to see if code follows the solenoid.
  10. If solenoid and wiring test good but intermittent fault persists, consider TCM/PCM driver failure and follow manufacturer procedures for module testing or replacement.
  11. Safety note: support vehicle securely and be cautious of hot fluids when checking transmission components.

Likely causes

  • Loose or corroded connector at solenoid C
  • Wiring harness damage (chafe, break, or intermittent short)
  • Failing solenoid (intermittent internal contact or coil)
  • Contaminated fluid/valve body restricting solenoid movement
  • Poor ground or intermittent supply voltage from PCM/TCM

Fault status

⚠️ Status
P0799 — Pressure Control Solenoid C Intermittent: intermittent/open/short or erratic signal detected in transmission pressure control solenoid C circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3 hours

Similar codes

P0795 P0796 P0797 P0798 P0700 P0741
320

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LAND ROVER

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