Code
P1795
INFINITI
P — Powertrain
Automatic Transmission System Malfunction
AI status
Completed
Completed
100%
Causes
- Low or contaminated automatic transmission fluid (ATF)
- Faulty transmission solenoids or valve body
- Wiring harness damage, poor connectors, or corroded grounds to the TCM or transmission
- Faulty Transmission Control Module (TCM) or incorrect software/calibration
- Faulty speed sensors (input/output) or torque converter clutch components
- Internal mechanical failure (clutches, bands, planetary gearset) or pressure loss
Symptoms
- Malfunction Indicator Lamp (MIL) / check engine light illuminated
- Erratic shifting, harsh or delayed shifts, slipping
- Transmission stuck in limp/torque-limited mode (reduced gears available)
- Unusual noises from transmission (whine, clunk) during shifts
- Lack of forward/reverse movement or inability to engage gears
- Transmission temperature or fault warnings
What to check
- Retrieve all current and stored codes and freeze-frame data with a compatible scan tool
- Inspect ATF level, color and smell; check for contamination or metal particles
- Visually inspect transmission harness connectors for corrosion, water intrusion or damage
- Check battery voltage and charging system under load
- Monitor live data: gear requested vs actual, input/output speed sensors, solenoid status
- Perform basic continuity and resistance checks on solenoid coils and harness circuits
Signal parameters
- TCM fault/trip flags and DTC list
- Shift solenoid ON/OFF commands and duty cycles (A, B, C etc.)
- Transmission fluid pressure (line pressure) if available
- Transmission input speed (TIS) and output speed (TOS)
- Engine RPM and vehicle speed vs commanded gear
- Torque converter clutch (TCC) command and actual state
Diagnostic algorithm
- Read and record all stored and pending DTCs and freeze-frame data; note conditions when code set.
- Clear codes and perform a controlled road test while monitoring TCM data to reproduce the fault.
- Check transmission fluid level/condition; top or replace fluid and filter if contaminated or low.
- Visually inspect wiring and connectors at the transmission and TCM; repair any damage or corrosion.
- Using a multimeter/ammeter, verify power, ground and continuity to solenoid pack and sensors; measure coil resistance and compare to spec.
- Command individual shift solenoids with a scan tool and observe response/pressure changes if pressure gauge available.
- Verify input/output speed sensors operation and correlation with wheel speed and engine RPM.
- Check for TCM software updates and compare TCM behavior to known service information; reflashing may be required.
- If electrical and hydraulic tests pass but issue persists, perform transmission pressure tests and inspect valve body/solenoid pack; consider valve body service or transmission rebuild.
- Replace faulty components only after confirming the cause (solenoids, sensors, harness, TCM). After repairs, clear codes and verify repairs with a final road test and scan.
Likely causes
- Leaking or low ATF causing low hydraulic pressure
- Shift solenoid pack failure or intermittent solenoid driver
- Connector corrosion or intermittent open/short in transmission harness
- TCM software fault or failed TCM
- Failed transmission oil pressure sensor or inaccurate pressure readings
Fault status
Status
Automatic transmission system malfunction detected by TCM. Diagnostic scan and inspection required; transmission may enter limp mode.
Repair difficulty: Hard
Diagnostic time: 2-8 hours
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