Failed stator temperature switch (thermistor) inside the transmission, reading low resistance or shorted; Damaged or chafed wiring harness between the switch and the transmission control module, often near the bellhousing or exhaust; Corroded or loose electrical connector at the transmission pass-through or at the TCM; Internal transmission fluid contamination or debris bridging the switch terminals; Faulty transmission control module, though this is less common than wiring or switch failure; Poor ground connection for the transmission or TCM causing a reference voltage drop

DTC codes / GM codes / P1873

P1873 · GMTCC Stator Temp Switch Circuit Low

Q: What does code P1873 mean?

TCC Stator Temp Switch Circuit Low. P1873 on a GM vehicle means the transmission control module has detected a low-voltage condition on the torque converter clutch stator temperature switch circuit. The switch is a thermistor that changes resistance with stator temperature, and the TCM interprets a signal below its expected range as a short to ground or an open circuit inside the switch. This code is specific to automatic transmissions that use a stator temperature sensor to protect the torque converter clutch from overheating.

P1873 on a GM vehicle means the transmission control module has detected a low-voltage condition on the torque converter clutch stator temperature switch circuit. The switch is a thermistor that changes resistance with stator temperature, and the TCM interprets a signal below its expected range as a short to ground or an open circuit inside the switch. This code is specific to automatic transmissions that use a stator temperature sensor to protect the torque converter clutch from overheating.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illuminated check engine light or transmission warning lamp, often with no other symptoms
Harsh or delayed torque converter clutch engagement, especially when the transmission is cold
Transmission may stay in a fixed gear or default to a limp-home mode in some applications
Poor fuel economy because the torque converter clutch may not lock up as designed
In rare cases, shudder or vibration during light-throttle cruising if the TCM misreads stator temperature

Common causes, most likely first

Failed stator temperature switch (thermistor) inside the transmission, reading low resistance or shorted
Damaged or chafed wiring harness between the switch and the transmission control module, often near the bellhousing or exhaust
Corroded or loose electrical connector at the transmission pass-through or at the TCM
Internal transmission fluid contamination or debris bridging the switch terminals
Faulty transmission control module, though this is less common than wiring or switch failure
Poor ground connection for the transmission or TCM causing a reference voltage drop

How to diagnose and fix it

Connect a scan tool and record the stator temperature PID to confirm the signal is stuck low or reading an implausible value
Inspect the transmission wiring harness and connectors for chafing, corrosion, or loose pins, especially near heat sources
Disconnect the stator temperature switch and measure its resistance with a multimeter, comparing to the expected curve for the current fluid temperature
Check the reference voltage and ground at the switch connector to rule out a TCM or harness supply problem
If the switch tests out of range, replace the stator temperature switch or the affected internal harness
Clear the code and perform a relearn or adaptive reset if the TCM requires it, then road test to verify the repair
If the code returns with good wiring and a known-good switch, diagnose the TCM with a factory scan tool and consider replacement only after confirming power and ground integrity

Why the stator temp switch fools many techs

A low signal does not always mean the switch itself has failed; a chafed harness wire shorting to ground on the exhaust or bellhousing is a frequent culprit that gets missed when the pan is dropped.
The stator temperature switch shares a reference circuit with other transmission sensors on some GM units, so a fault in a neighbouring sensor can pull the voltage down and set P1873 without the stator switch being defective.
Technicians often replace the TCM first because the code points to a circuit fault, but the TCM is rarely the cause; always verify the switch resistance and wiring continuity before condemning the module.
On some applications the stator temperature signal is only used for torque converter clutch protection, so the vehicle may drive normally and the code may be the only clue that the circuit is compromised.
Fluid contamination from a failing torque converter or neglected service can coat the switch and connector, causing a low-resistance path that mimics a failed sensor.

Can I keep driving with P1873?

You can usually continue driving to a repair shop because the transmission remains functional, but avoid heavy towing or sustained high-load driving that would rely on torque converter clutch protection. If the transmission enters limp mode or shifts harshly, have it checked promptly to prevent further damage.

Tools that help

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