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DTC codes / Honda codes / P1753

P1753 · HondaTCM A/T ECT Sensor Circuit Fault

P1753 on Honda vehicles means the Transmission Control Module (TCM) has detected an abnormal signal from the automatic transmission fluid temperature sensor, which Honda calls the A/T ECT sensor. The TCM expects a specific voltage range that changes with fluid temperature, and the circuit is reporting a value outside that expected range.

SystemPowertrain
Code typeHonda specific
SeverityMedium
Fix difficultyIntermediate
AreaTransmission

Symptoms you may notice

  • Illuminated Check Engine Light or Transmission Warning Light, often with no other symptoms
  • Harsh or delayed shifting when the transmission is cold, because the TCM substitutes a default temperature value
  • Torque converter clutch may not engage normally until the fluid warms up
  • Transmission may stay in a single gear or enter limp mode in severe cases
  • Inaccurate or erratic temperature reading on a scan tool data stream

Common causes, most likely first

  1. Faulty A/T ECT sensor (transmission fluid temperature sensor) inside the transmission
  2. Damaged or corroded wiring harness between the sensor and the TCM
  3. Loose or contaminated sensor connector pins
  4. Open or shorted sensor circuit due to chafed wiring near the transmission case
  5. Failed TCM driver circuit for the sensor input
  6. Low or severely degraded automatic transmission fluid affecting sensor response

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data for P1753, then clear the code and verify it returns
  2. Inspect the A/T ECT sensor connector and harness for corrosion, looseness, or chafing
  3. Measure sensor resistance at the connector and compare to the Honda temperature-resistance chart
  4. Backprobe the sensor signal wire at the TCM and check voltage while wiggling the harness
  5. Check for continuity and short-to-ground on both sensor wires from the sensor to the TCM
  6. Replace the A/T ECT sensor if resistance is out of specification or the signal is erratic
  7. If wiring and sensor test good, test the TCM input circuit and replace the TCM only as a last resort

What Honda techs check before replacing the sensor

  • A common misdiagnosis is replacing the A/T ECT sensor when the real fault is a chafed wire near the transmission mount or a corroded connector pin that only acts up when hot or wet.
  • Honda TCMs often set P1753 when the sensor circuit is intermittently open, so a resistance check with a cold transmission can pass while the fault appears only after the fluid reaches operating temperature.
  • The A/T ECT sensor shares its ground or signal path with other transmission sensors on some Honda models, so a fault in a related circuit can trigger P1753 without the sensor itself being bad.
  • After replacing the sensor or repairing wiring, the TCM may need a relearn or a short drive cycle before the code stays cleared, and clearing codes without checking freeze-frame data can send you chasing the wrong part.
  • Low transmission fluid or fluid contaminated with coolant or debris can skew the temperature sensor reading and set P1753 even when the sensor and wiring are electrically perfect.

Can I keep driving with P1753?

You can usually drive short distances at moderate speeds, but avoid heavy towing or aggressive driving because the TCM may use a default fluid temperature and shift harshly. If the transmission enters limp mode or slips, stop driving and have it diagnosed promptly.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Honda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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