P0669

PCM/ECM/TCM Internal Temperature Sensor Circuit High

P0669 is a generic OBD-II powertrain diagnostic trouble code: PCM/ECM/TCM Internal Temperature Sensor Circuit High. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0669
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P0669 means

P0669 is the high-side counterpart to P0668, set when the control module detects that its internal temperature sensor circuit voltage has risen above the maximum expected threshold. The built-in sensor monitors the module's own temperature to keep it within its optimal operating range, and the module compares the signal against calibrated limits.

A signal stuck high typically indicates an open circuit in the sensor path, a failed sensor element, shorted or corroded wiring, a power or ground problem, or an internal module hardware fault. While the sensing element is inside the module, the reference circuit, connector, grounds, and module supply can all drive the reading high, so external inspection remains part of the diagnosis. The code is often misread as a real overheating problem when it is actually an electrical fault in the sensing circuit.

With the signal stuck high the module may interpret the condition as extreme overtemperature and engage protective strategies unnecessarily, or simply log the fault. Sources note that left untreated the condition can lead to erratic behavior, reduced engine power, and even stalling, so it should be diagnosed rather than ignored.

Common causes

Most-frequently reported root causes when P0669 is logged.

  • 1
    Open circuit in the internal temperature sensor path driving the signal high.
  • 2
    Failed internal temperature sensing element reading high.
  • 3
    Shorted or corroded wiring in the sensor circuit.
  • 4
    Poor module power supply or ground affecting the reference voltage.
  • 5
    Corroded, damaged, or loose module connector pins.
  • 6
    Moisture or contamination inside the module affecting the reference circuit.
  • 7
    Module hardware fault driving the internal sensor signal to rail voltage.
  • 8
    Corrupted module software misapplying the upper-limit comparison.

Symptoms drivers notice

Check engine light or transmission warning lamp illuminated.
Often no immediate drivability symptoms in mild cases.
Reduced engine power or erratic behavior in some cases.
Possible engine stalling if protective strategies engage.
Companion internal module codes may be stored.

How to diagnose P0669

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all DTCs and freeze frame data, noting any other internal module codes.
  2. 2
    Perform a visual inspection of the module wiring and grounds for damage, shorts, or corrosion.
  3. 3
    Inspect the module connector for corrosion, moisture, and damaged pins.
  4. 4
    Verify module power supply and ground voltages meet specification.
  5. 5
    Read the internal temperature value in live data if supported and compare to actual ambient or underhood temperature.
  6. 6
    Apply a module software or calibration update if one is available for this fault.
  7. 7
    If wiring and power are good but the fault persists, evaluate the module for internal hardware failure.

Related powertrain codes

Frequently asked questions

What is the difference between P0668 and P0669?

P0668 is a circuit-low fault where the signal is below the minimum threshold, while P0669 is a circuit-high fault where the signal is above the maximum threshold.

Can P0669 cause the engine to shut down?

It can. If the module reads the high signal as extreme overtemperature it may reduce power or stall the engine, though outcomes vary by vehicle.

Is there external wiring to check for P0669?

Yes. Shorted or corroded wiring, poor grounds, and connector faults can drive the reading high, so inspect the harness and connector before condemning the module.

Will the code return after clearing?

Yes. If the underlying fault is still present, the code will reset once the module completes its self-diagnostic cycle.

Disabling P0669 in software

RaceTune can permanently disable P0669 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

ECU families we can disable P0669 on

We hold the DaVinci A2L disable definitions for these families, so the exact P0669 path and mask addresses are mapped. verified marks a confirmed disable definition. We support many more — upload your file and our identifier will match it automatically.

  • Bosch EDC17C66 verified
  • Bosch EDC17CP57 verified

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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