P1773
Automatic Transmission System Malfunction.
- Honda
- 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 Honda vehicles P1773 is logged as an automatic transmission system malfunction. The transmission control logic (the PCM or a separate transmission control unit, depending on model) has detected a fault it cannot attribute to a more specific code. The exact test that sets it varies by model, year and gearbox type, so check the manufacturer service information for the vehicle in question.
Symptoms
- Transmission warning light or D indicator flashing on the dash
- Harsh, delayed or flared gear changes
- Transmission stuck in one gear (limp mode)
- Torque converter shudder or unusual engine revs at cruise
- Poor fuel economy
- Check engine light on
Possible causes
- Low, degraded or contaminated transmission fluidlikely
- Faulty or sticking shift or lock-up solenoid, or a restricted valve body passagelikely
- Damaged wiring or poor connector contact between the transmission and its control unit (chafing, corrosion, water ingress)likely
- Faulty transmission speed or range sensor giving an implausible signalpossible
- Weak battery or charging fault causing low supply voltage to the control unitspossible
- Internal transmission wear (clutch packs, torque converter) causing slip or pressure losspossible
- Faulty control unit or outdated software where the manufacturer has issued a bulletin for itrare
How to diagnose
- Scan all control units, record the freeze frame data and note any other transmission, engine or network codes stored alongside P1773.
- Check the battery condition and charging voltage, as low voltage can upset transmission control.
- Check the transmission fluid level and condition against the manufacturer's procedure for that gearbox, looking for burnt smell, debris or discolouration.
- Inspect the transmission wiring harness and connectors for chafing, corrosion, oil contamination and loose pins.
- Use live data to compare input and output speed sensor readings, gear selection and solenoid commands against expected values.
- Test solenoid and sensor resistance and circuit integrity against the specifications in the service information.
- Check for manufacturer technical bulletins and software updates relevant to the model and gearbox.
- If the electrical side is sound, carry out a pressure test or road test per the service information to assess internal condition.
How to fix
- Correct the fluid level or replace the fluid with the specified type if it is degraded or contaminated.
- Repair or replace damaged wiring and clean or replace faulty connectors.
- Replace any faulty solenoid, speed sensor or range sensor confirmed by testing.
- Clean or replace the valve body components if passages are blocked or sticking.
- Update or reflash the control unit software only if a known bulletin applies, or replace a confirmed faulty control unit.
- Repair or overhaul the transmission if testing shows internal wear or pressure loss.
Can I keep driving?
The car can usually be driven short distances carefully, but fix it soon as continued slipping or harsh shifting can cause expensive internal damage. If it is in limp mode, slipping badly or the warning light is flashing, limit driving and have it checked promptly.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.