Wiring or connector fault in the transmission control circuits (chafed, corroded or loose terminals); Low, degraded or contaminated transmission fluid affecting hydraulic control; Faulty shift or pressure solenoid, or a sticking valve body component; Faulty transmission speed, range or temperature sensor feeding the control unit; Low or unstable battery or supply voltage upsetting the control unit; Internal mechanical wear (clutches, torque converter) causing a control mismatch; Fault in the transmission control unit itself or an outdated calibration, where the manufacturer lists it as a known cause.

P1773

Automatic Transmission System Malfunction.

Infiniti
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
7: AreaTransmission
73: FaultThe specific fault in that area

What it means

On Infiniti, P1773 is listed as an automatic transmission system malfunction. The transmission control unit has detected a fault in the transmission control system and stored the code. The exact circuit or condition that triggers it varies by model, transmission and year, so confirm it against the correct service information and any other stored codes.

Symptoms

Transmission warning light or malfunction indicator lamp on
Harsh, delayed or flared gear changes
Transmission stuck in one gear (limp mode)
Loss of gears or no kickdown
Reduced performance or poor fuel economy
Shift selector position not matching the gear engaged

Possible causes

Wiring or connector fault in the transmission control circuits (chafed, corroded or loose terminals)likely
Low, degraded or contaminated transmission fluid affecting hydraulic controllikely
Faulty shift or pressure solenoid, or a sticking valve body componentpossible
Faulty transmission speed, range or temperature sensor feeding the control unitpossible
Low or unstable battery or supply voltage upsetting the control unitpossible
Internal mechanical wear (clutches, torque converter) causing a control mismatchrare
Fault in the transmission control unit itself or an outdated calibration, where the manufacturer lists it as a known causerare

How to diagnose

Read all stored codes and freeze frame data, noting any other engine or transmission codes and the conditions when P1773 was set
Check the transmission fluid level, condition and smell, following the procedure for that model, as some have no dipstick
Inspect the transmission wiring, connectors and earth points for damage, water ingress, corrosion or oil contamination
Test battery condition and charging voltage, as low voltage can cause spurious transmission faults
Check live data for speed sensors, range switch, fluid temperature and solenoid commands for implausible values
Test the resistance and operation of the relevant solenoids and sensors against the manufacturer's specifications
Check for technical service bulletins or calibration updates for the vehicle and transmission
Carry out a pressure test or road test with data logging if the electrical checks find nothing

How to fix

Repair or replace damaged wiring, connectors or terminals found in the transmission circuits
Correct the fluid level or replace the fluid and filter using the specified type, if it is degraded or contaminated
Replace a faulty solenoid, valve body component or sensor confirmed by testing
Restore correct battery and charging system performance
Update or reflash the control unit calibration only if the manufacturer lists it as the fix for this fault
Repair or overhaul the transmission if an internal mechanical fault is confirmed

Can I keep driving?

Medium severity

The car can usually be driven cautiously for a short time to get it checked, but it may go into limp mode and the fault can worsen. Avoid heavy loads, towing and hard acceleration, and stop if shifting becomes severe, slips or the transmission overheats.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.