Network, generic

U066D Lost Communication With Charge Air Cooler Temperature Sensor Bank 1

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

The temperature of the charge air behind the intercooler tells the engine controller how dense the intake charge is and whether the cooler still removes enough heat; CARB lists charge air cooler temperature in the data diesel vehicles must report and requires an undercooling monitor in (f)(7.2.4). U066D is reserved for a bank 1 sensor that delivers its reading as a digital frame, for example as the NTC channel of a SENT pressure sensor such as Infineon's KP276. No manufacturer documents U066D publicly: Ford (2024 gasoline, 2023 diesel) and GM (25OBDG04A, Type B) read their bank 1 sensors analog and set P007C/P007D when voltage or resistance leaves its range. Without the value the controller works from a model, and boost may be trimmed.

Likely causes

Signal or supply wire to the charge air sensor open or chafed

Oily or corroded connector at the charge air pipe

Digital sensor (often combined with boost pressure) failed

Engine controller input or software fault

Symptoms

Check engine light
Slightly reduced power at high load
Often no noticeable change in normal driving

Repair estimate

DifficultyEasyDIY possible

Parts and labour€40–300

Time0.3–1.5 h

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

Parts involved

cac temp sensor bank 1vehicle bus wiring

References: law.cornell.edu, fordservicecontent.com, gsi.ext.gm.com, infineon.com.