P0667 – PCM/ECM/TCM Internal Temperature Sensor Range/Performance

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: Range/Performance

Definition source: SAE J2012/J2012DA (industry standard)

P0667 indicates a range/performance problem with the control module’s internal temperature sensor inside the PCM/ECM/TCM. In practical terms, the module has detected that its internally measured temperature signal is implausible, slow to respond, inconsistent with related operating conditions, or otherwise outside expected behavior for the way the vehicle is being driven and the environment it’s in. Because monitoring strategy, thresholds, and where the temperature sensor is implemented can vary by vehicle, always confirm the exact enable conditions and test procedures in the correct service information. This DTC does not, by itself, prove the control module has failed; it only tells you the temperature-sensing input as interpreted by the module failed a plausibility check.

What Does P0667 Mean?

P0667 – PCM/ECM/TCM Internal Temperature Sensor Range/Performance means the powertrain control system has identified that the internal temperature sensor signal used by the PCM/ECM/TCM is not performing within an expected operating range or is not behaving plausibly. Under SAE J2012 DTC conventions, this is a range/performance (plausibility) fault rather than a hard “circuit high/low/open” electrical fault. The module is essentially saying the internal temperature reading it relies on for self-protection and strategy decisions does not correlate properly with time, operating conditions, or other information the module uses to validate the reading.

Quick Reference

• Subsystem: PCM/ECM/TCM internal temperature sensing and plausibility monitoring (module self-monitor).
• Common triggers: Temperature signal that is stuck, skewed, slow to change, or inconsistent with operating conditions; unstable module power/ground affecting sensor interpretation; thermal stress events (varies by vehicle).
• Likely root-cause buckets: Power/ground integrity, connector/terminal issues at the module, harness damage affecting module feeds, charging system irregularities, module internal sensor/logic faults, software/calibration issues (varies by vehicle).
• Severity: Varies; may be mild (MIL only) or lead to reduced power/torque management, shift changes, or protective strategies depending on platform.
• First checks: Scan for related DTCs, verify battery/charging health, inspect module connectors for fit/corrosion/water intrusion, confirm power/ground voltage-drop under load, review freeze-frame and monitor behavior.
• Common mistakes: Replacing the control module without verifying power/ground quality, ignoring charging system ripple/voltage instability, and treating a plausibility DTC like a simple open/short.

Theory of Operation

The PCM/ECM/TCM typically includes an internal temperature sensor used to estimate control-module temperature for strategy management and self-protection. The module samples this signal and uses it to adjust internal diagnostics, manage protective actions (such as limiting certain functions), and validate that internal operating conditions remain within acceptable bounds.

For a range/performance monitor, the module does not only look for an electrical “high” or “low.” Instead, it evaluates whether the temperature value changes in a believable way over time and whether it correlates with other information (for example, time since key-on, ambient influence, under-hood heat soak, or operating load—exact correlations vary by vehicle). If the internal temperature reading appears stuck, biased, noisy, or inconsistent with expected thermal behavior, the module can set P0667.

Symptoms

• MIL/Check engine illuminated, possibly intermittent depending on operating conditions.
• Reduced power or torque management/limp strategy if the module enters a protective mode (varies by vehicle).
• Shift quality changes or transmission strategy adjustments when the fault is associated with a TCM function (varies by vehicle).
• Intermittent operation that appears after heat soak, extended driving, or during high electrical load events (not definitive, requires testing).
• Multiple DTCs present alongside P0667, especially if power/ground stability is compromised.
• Warning messages related to powertrain performance or control-system protection (wording varies by vehicle).

Common Causes

• Intermittent power or ground supply issues to the PCM/ECM/TCM causing the internal temperature signal to become implausible
• High resistance in module power/ground circuits (corrosion, loose fasteners, poor terminal tension) leading to abnormal internal heating or unstable readings
• Poor connector pin fit, fretting, or corrosion at the PCM/ECM/TCM connectors creating intermittent reference/ground integrity problems that affect internal sensor plausibility
• Harness damage near the module (chafing, pinch points, prior repair splices) creating intermittent opens or resistance changes that disrupt normal module operation
• Charging system irregularities (unstable alternator output, poor battery connections) that can stress the module and skew internal temperature sensor behavior
• Cooling/airflow issues around the control module area (blocked airflow, heat soak, proximity to heat sources) contributing to temperature behavior outside expected performance patterns
• Module internal fault affecting the internal temperature sensor element or its internal signal processing (not confirmed without testing)
• Calibration/software issue or logic sensitivity (varies by vehicle) that can set a range/performance fault when the temperature response is slower/faster than expected

Diagnosis Steps

Tools typically needed include a scan tool with live-data logging and freeze-frame access, a digital multimeter, and basic back-probing supplies. A battery/charging system tester is helpful for confirming stable electrical supply. Access to vehicle-specific service information is important because the internal temperature PID names, enabling criteria, and related power/ground pinouts vary by vehicle.

1. Confirm the DTC and capture freeze-frame data and all stored/pending codes. Record conditions such as run time, ambient conditions, and any related power supply or module communication DTCs that could influence this monitor.
2. Check for an active warning strategy (reduced power, module protection mode) and verify the customer complaint. If multiple modules are setting supply-related or communication codes, prioritize diagnosing those first because they can indirectly trigger internal temperature range/performance faults.
3. Review service information for the monitor description, enabling conditions, and the scan tool PID(s) for the PCM/ECM/TCM internal temperature sensor. Identify any related PIDs (battery voltage, module voltage, 5V references if applicable, ignition status) used for plausibility checks.
4. Perform a thorough visual inspection of the control module area: connector latches fully seated, no water intrusion, no pushed-out pins, no damaged harness insulation, and no evidence of prior repairs. Correct any obvious issues before deeper testing.
5. Key off, then key on: verify battery state of charge and check charging system basics per service information. Look for signs of unstable supply that could skew module internal temperature performance (poor battery terminals, loose grounds, charging irregularities).
6. With the engine running, monitor live data and log the internal temperature PID along with battery/charging voltage and any related temperature PIDs available. Look for implausible behavior such as a stuck value, erratic jumps, or a response that does not change reasonably with operating conditions (exact expectations vary by vehicle).
7. Perform a controlled wiggle test while logging data: gently manipulate the harness near the PCM/ECM/TCM connectors, main grounds, and power distribution points. If the internal temperature PID glitches or the DTC resets, isolate the affected section and inspect for terminal tension, corrosion, and conductor damage.
8. Conduct voltage-drop testing on the module power and ground circuits under load (engine running, electrical loads on). Measure across the power feed path and across the ground path to identify excessive resistance. Repair any high-resistance connections found (service information defines test points and acceptable results).
9. If service information indicates dedicated ignition feeds, constant feeds, or multiple grounds, test each one individually for integrity. Confirm the module sees stable supply during cranking as well, since some range/performance faults occur during start events.
10. Clear codes and perform a road test under conditions that match the freeze-frame as closely as practical while logging the internal temperature PID. Confirm whether the monitor completes and whether the fault returns; if it only returns after heat soak or extended operation, repeat the test after a controlled heat soak period.
11. If wiring, connectors, and power/ground tests pass and the fault repeats, follow service information for module-level checks (software level verification, reprogramming if applicable, and confirmation tests). Only after completing these steps should internal module fault be considered as the likely cause.

Professional tip: Treat P0667 as a plausibility/range-performance problem, not a simple “bad sensor” conclusion. The internal temperature signal is heavily influenced by module power/ground quality and charging stability, so prove electrical integrity with voltage-drop testing and repeatable data logs before considering module replacement or programming actions.

Possible Fixes & Repair Costs

Repair cost varies widely because P0667 is a range/performance fault tied to an internal module temperature signal, and the true cause can be power/ground integrity, connector issues, thermal management concerns, or a control module problem. Accurate diagnosis determines whether the repair is simple reconditioning or a module-level solution.

• Restore power and ground integrity to the control module: Clean/secure connections, repair damaged wiring, and correct excessive voltage drop found during testing.
• Repair connector and terminal issues: Address corrosion, moisture intrusion, loose pin fit, bent terminals, or poor crimps at module connectors and related junctions.
• Correct harness routing/heat exposure problems: Re-route, re-loom, or protect wiring that is heat-soaked or chafing and causing intermittent signal plausibility faults.
• Address cooling/airflow issues around the module: Verify vents, ducts, shields, and mounting location are not blocked and that surrounding heat sources are not creating abnormal thermal conditions (varies by vehicle).
• Perform module software update or configuration actions: If service information calls for it, complete reprogramming, relearn, or calibration steps after confirming power/ground stability.
• Replace the affected control module: Consider only after confirming external circuits, power/ground, and environmental factors are correct and the fault is repeatable.

Can I Still Drive With P0667?

Sometimes the vehicle will remain drivable, but P0667 involves internal temperature sensor range/performance within a control module, so risk depends on whether the module enters a protective strategy. If you notice reduced power, warning lights for multiple systems, transmission shifting concerns, stalling, no-start, or any brake/steering warnings, do not drive—have it diagnosed and towed if necessary.

What Happens If You Ignore P0667?

Ignoring P0667 can lead to intermittent or worsening drivability issues if the control module limits operation to protect itself, and repeated thermal-related plausibility failures can trigger additional fault codes and disable some functions. Continued operation without diagnosis may also mask an underlying power/ground or connector issue that can become more severe over time.

Related Sensor Pcm/ecm/tcm Codes

Compare nearby sensor pcm/ecm/tcm trouble codes with similar definitions, fault patterns, and diagnostic paths.

• P0C4E – Motor Control Module “B” Internal Temperature Sensor Circuit Range/Performance
• P0666 – PCM/ECM/TCM Internal Temperature Sensor Circuit
• P0514 – Battery Temperature Sensor Circuit Range/Performance
• P0196 – Engine Oil Temperature Sensor Range/Performance
• P051B – Crankcase Pressure Sensor Circuit Range/Performance
• P0933 – Hydraulic Pressure Sensor Range/Performance

Key Takeaways

• P0667 is a range/performance fault tied to the control module’s internal temperature sensor signal plausibility, not automatically a failed module.
• Start with basics: power/ground voltage-drop testing and connector/terminal inspection are high-value first steps.
• Heat and intermittents matter: harness routing, heat exposure, and poor pin fit can cause skewed or implausible readings.
• Confirm repeatability: use scan tool logging and operate under similar conditions to when the code sets.
• Module replacement is last: only after external causes and required configuration/software steps are ruled out.

Vehicles Commonly Affected by P0667

• Vehicles with tight engine-bay packaging where control modules are exposed to higher heat soak
• Applications with underhood-mounted controllers positioned near exhaust or other heat sources
• High-mileage vehicles with aging grounds, fretting terminals, or connector moisture exposure
• Vehicles operated in extreme ambient temperatures (hot climates, heavy stop-and-go, prolonged idling)
• Vehicles with recent electrical repairs where connectors were disturbed or grounds were relocated
• Vehicles with prior water intrusion events affecting connectors, splices, or module housings
• Vehicles used for towing or heavy loads that experience elevated underhood temperatures
• Vehicles with added electrical accessories that may impact power/ground stability if installed improperly

FAQ

Does P0667 mean the PCM/ECM/TCM is bad?

No. P0667 indicates the module detected an internal temperature sensor range/performance (plausibility) problem. That can be caused by power/ground instability, connector/terminal issues, heat-related intermittents, or software conditions, in addition to an internal module fault.

What makes a “range/performance” code different from “circuit high/low”?

Range/performance faults generally mean the signal is implausible compared to expected behavior, correlation, or response over time rather than being clearly shorted high, shorted low, or open. Diagnostics focus on stability, intermittents, and environmental/operating conditions, not just a single static electrical state.

Will clearing the code fix P0667?

Clearing may turn the light off temporarily, but if the underlying plausibility problem remains, the monitor can fail again. Use clearing only after recording freeze-frame data and after repairs, then confirm with a drive cycle and scan tool logging.

Can a weak battery or charging issue cause P0667?

Yes, it can contribute. If system voltage is unstable or grounds have excessive voltage drop, internal module references and temperature calculations can become implausible and trigger a range/performance fault. Verify battery condition, charging performance, and clean, tight ground paths.

What’s the most important first test for P0667?

Perform power and ground voltage-drop testing to the affected control module while the vehicle is running and during load changes, then inspect connectors for corrosion or poor pin fit. This targets common, correctable causes that can mimic an internal sensor plausibility issue.

After repairs, confirm the fix by repeating the conditions that originally set P0667 and reviewing a live-data log to ensure the internal temperature reading behaves consistently without sudden jumps or implausible changes.