U066D code meaning
Lost Communication With Charge Air Cooler Temperature Sensor Bank 1
Network system Generic code U06xx codes Check engine light
What U066D means
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.
U066D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U066D
- Check engine light
- Slightly reduced power at high load
- Often no noticeable change in normal driving
Common causes of U066D
- Most likelySignal or supply wire to the charge air sensor open or chafed
- PossibleOily or corroded connector at the charge air pipe
- PossibleDigital sensor (often combined with boost pressure) failed
- Less likelyEngine controller input or software fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cac temp sensor bank 1Vehicle bus wiring
What each part of U066D means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6D | The exact fault in that area. |
What to do next
- Note U066D and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U066D
What does U066D mean?
U066D means "Lost Communication With Charge Air Cooler Temperature Sensor Bank 1". 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). It is a generic code, so it means the same on every make.
Is it safe to drive with U066D?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U066D fail an emissions test?
Yes, it can. U066D is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U066D to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U066D clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.