Powertrain, generic · Computer and auxiliary outputs

P0669 Control Module Internal Temperature Sensor A Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

Control modules measure their own circuit board temperature with an internal sensor to protect output stages (overtemperature is P0634) and, in GM transmission modules, as a substitute for fluid temperature. In GM's 6T70/6T75 and related automatics the sensor sits in the transmission module inside the valve body, with no external wiring – so the repair is practically always the module or valve body assembly. P0669 means the sensor signal is at the high voltage end (internal open or short to voltage): GM treats a converted value of 249 °C or more for 60 s as a fault, with the lamp after two trips and the power-up temperature as substitute. Unlike P0634, which reports a plausibly high real temperature (GM: 142 °C), P0669 reports a physically impossible value.

Likely causes

Module faulty internally (sensor open)
Moisture or corrosion in the electronics
Module supply or software

Symptoms

  • Warning lamp
  • Changed shift quality (substitute value)
  • Scan tool shows an implausibly high module temperature

Repair estimate

DifficultyHardWorkshop job
Parts and labour€400–1,500
Time2–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

transmission control modulecontrol module internal temperature sensor

Related codes

P0668P0667P0666P0634P0713

References: law.cornell.edu, gsi.ext.gm.com, saabwisonline.com.