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DTC codes / U06xx · Network communication / U066E

U066ELost Communication With Charge Air Cooler Temperature Sensor Bank 2

U066E is a generic network communication code indicating that a control module on the vehicle's CAN (Controller Area Network) bus has lost contact with the charge air cooler temperature sensor for bank 2. The module monitoring this sensor, typically the engine control module or a dedicated powertrain module, has stopped receiving valid temperature data over the communication network, which can affect fuel delivery and turbocharger control strategies.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) on the dashboard, often with no other noticeable symptoms
  • Reduced engine performance or a limp-home mode if the missing temperature data forces the powertrain control strategy into a default state
  • Poor fuel economy or altered turbocharger boost behavior because the computer cannot accurately calculate charge air density
  • Intermittent rough running or hesitation under acceleration when the sensor signal drops out sporadically
  • A stored code in multiple modules if the communication loss affects shared bus traffic rather than a single sensor circuit

Common causes, most likely first

  1. Damaged, corroded, or disconnected wiring or connector at the bank 2 charge air cooler temperature sensor
  2. Failed charge air cooler temperature sensor itself, causing an open or short in its internal circuit
  3. Faulty CAN bus wiring between the sensor's control module and the rest of the network, including chafed or broken conductors
  4. Poor ground connection or voltage supply issue at the module that reports the sensor data
  5. Software or calibration fault in the control module that interprets the sensor signal, requiring a reflash or update
  6. Failed control module on the network that has stopped transmitting or receiving data properly

How to diagnose and fix it

  1. Inspect the bank 2 charge air cooler temperature sensor connector and wiring for corrosion, looseness, or physical damage, and repair as needed
  2. Measure the sensor's resistance or voltage output with a multimeter and compare it to the manufacturer's specification to confirm sensor health
  3. Check the CAN bus wiring for continuity and shorts using a wiring diagram, focusing on the segment between the sensor's module and the network backbone
  4. Verify power and ground at the control module that reports the sensor data, including fuse and relay checks
  5. Clear the code and perform a road test to see if the fault returns, monitoring live data for the charge air cooler temperature signal
  6. If the sensor and wiring test good, check for technical service bulletins or software updates for the affected module
  7. As a last resort, substitute a known-good module or sensor to isolate an intermittent internal failure before replacing expensive components

What most technicians overlook on U066E

  • A charge air cooler temperature sensor that reads plausibly but intermittently drops off the bus can set U066E without ever storing a sensor-specific code, so live data graphing during a wiggle test is more revealing than a static scan.
  • This code often appears after a repair that disturbed the harness near the charge air cooler, such as an intercooler replacement or front-end work, and the root cause is a partially seated connector rather than a failed sensor.
  • Some vehicles use a shared temperature sensor that reports both bank 1 and bank 2 data through a single module, so a U066E can be triggered by a fault on the bank 1 side of the same circuit if the module multiplexes the signals.
  • A weak or failing battery or charging system can cause modules to drop off the CAN bus intermittently, setting communication codes like U066E that disappear after a battery replacement and a code clear.
  • Do not replace the charge air cooler temperature sensor solely on the basis of U066E; the code indicates lost communication, not necessarily a dead sensor, and the fault frequently lies in the wiring or the reporting module.

Can I keep driving with U066E?

You can generally continue driving with U066E because the engine will default to a safe calibration, but avoid heavy acceleration or towing until the fault is repaired. If the vehicle enters limp mode or runs poorly, have it diagnosed promptly to prevent potential damage to the turbocharger or aftertreatment system.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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