OBD Guide
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P0666

Control Module Internal Temperature Sensor A Circuit

P0666 is an OBD-II diagnostic trouble code meaning: Control Module Internal Temperature Sensor A Circuit. Common causes: internal fault of the ecu temperature sensor (defect or degradation), previous ecu overheating, damaged sensor. Estimated repair cost: $33–889.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$33–889 (est.)

Symptoms

  • Check Engine light comes on
  • Engine runs fine in most modes
  • Possible interruptions at high ambient temperatures
  • Diagnostic code only without obvious symptoms (early stage)
  • Possible P0667 codes at the same time

Causes

  • Internal fault of the ECU temperature sensor (defect or degradation)
  • Previous ECU overheating, damaged sensor
  • Manufacturing defect in the electronic circuit of the ECU
  • Mechanical damage to the ECU board
  • Moisture trapped inside the ECU

How to Fix

  1. Check the ECU location for overheating (insufficient ventilation, proximity to hot parts)
  2. Check the correct installation and fastening of the ECU
  3. Make sure there are no traces of moisture or corrosion on the ECU connectors.
  4. ECU diagnostics on a specialized stand
  5. If an internal malfunction is confirmed, repair or replace the ECU

Related codes

P0667P0600P0604P0605P0606

Error P0666 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P0666 code mean?

P0666 is an OBD-II diagnostic trouble code that indicates: Control Module Internal Temperature Sensor A Circuit

What causes a P0666 error code?

The most common causes of P0666 include: Internal fault of the ECU temperature sensor (defect or degradation); Previous ECU overheating, damaged sensor; Manufacturing defect in the electronic circuit of the ECU; Mechanical damage to the ECU board.

How do I fix a P0666 diagnostic trouble code?

To fix P0666: Check the ECU location for overheating (insufficient ventilation, proximity to hot parts). Check the correct installation and fastening of the ECU. Make sure there are no traces of moisture or corrosion on the ECU connectors.. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0666?

Limited driving only, diagnose soon

How much does it cost to fix P0666?

The estimated repair cost for P0666 is $33–889. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat