U11E9 – Lost Communication With Active Grill Shutter (Chrysler)

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By Reinier (Contact Me)
Last Updated 2023-10-02
Automobile Repair Shop Owner
CodeFault LocationProbable Cause
U11E9 Lost Communication With Active Grill Shutter (Chrysler)
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Table of Contents

  1. What Does Code U11E9 Mean?
  2. Where is the U11E9 sensor located?
  3. What are the common causes of code U11E9?
  4. What are the symptoms of code U11E9?
  5. Get Help with U11E9

What Does Code U11E9 Mean?

OBD II fault code U11E9 is a manufacturer-specific code that is defined by carmakers Chrysler, Jeep, Dodge, Fiat, and RAM as U11E9 – “Lost Communication With Active Grill Shutter”, and is set when the PCM (Powertrain Control Module) detects a loss of communication between itself and the actuator that controls the Active Grill Shutter.

Although the primary function of active grill shutters is to improve the aerodynamics of vehicles by deflecting the airflow around a moving vehicle instead of allowing the airflow to enter the engine compartment where it acts as a brake on the vehicle, active grill shutters have other important, albeit secondary functions.

For example, active grill shutters reduce engine warm-up times by preventing air from flowing through the radiator when the shutters are closed. More importantly, though, active grill shutters also greatly reduce aerodynamic lift balance, which is a phenomenon that tends to lift the front of the car at high road speeds. This phenomenon is caused by the air stream that enters the engine compartment where it is somewhat compressed by the vehicle’s high rate of forward motion. Moreover, the trapped air in the engine compartment also causes significant turbulence in the air that flows around a moving vehicle, which acts as a braking mechanism on the vehicle that increases fuel consumption and harmful exhaust emissions.

In terms of operating principles, the PCM collects input data from several engine sensors, such as (among others) the transmission fluid temperature sensor, the engine coolant sensor, the engine speed sensor, and the A/C system pressure to determine suitable and appropriate active grill shutter strategies.

For example, the shutters will typically not open when the engine coolant is below a certain threshold, or close when the engine coolant temperature is above a maximum allowable threshold. Similarly, the shutters will open when the automatic transmission fluid reaches a maximum allowable threshold to allow for improved cooling of the transmission fluid through the radiator. We could list other examples here, but the point is that while the enabling conditions for active grill operation vary between vehicles, all required enabling conditions must be met before the PCM will activate the shutters in any direction.

It is worth pointing out that despite any other functions and benefits active grill shutters might have, efficient engine cooling largely depends on the active grill shutters working as both designed and expected. For instance, if the shutters are locked or stuck in the closed position, it will be impossible for the radiator to shed heat into the atmosphere, and the engine will overheat very quickly.

Thus, if a fault or malfunction occurs in the circuits that prevent the PCM from communicating with the grill shutter’s actuator via a serial communications network, the PCM will recognize that it cannot manage the engine’s temperature (and other functions) effectively and it will set code P11E9 and possibly also illuminate a warning light upon first detecting the communications failure.

Where is the U11E9 sensor located?

Although this image does not show the actual grill shutters on this late-model Ram truck, this image does show the effect of the active grill shutters (that are located behind the outer grille) when they are in the closed position. In this wind tunnel demonstration, the air flowing over the truck is represented by the white smoke, which flows over the hood instead of into the engine compartment.

Note that since the shutters are in the closed position, no air can pass through the radiator, which could cause the engine to overheat fatally within a few seconds.

What are the common causes of code U11E9?

Some common causes of code P11E9 could include one or more of the following-

  • Damaged, burnt, shorted, disconnected, or corroded wiring and connectors in the circuits that monitor and control the active grill shutters
  • Failure to perform a shutter relearn procedure after replacing or repairing the active grill shutters or their actuator
  • Improperly installed replacement grill shutters
  • Defective or malfunctioning active grill shutter actuator
  • The presence of accumulated debris or snow in the shutters
  • One or more defective or malfunctioning engine sensors
  • Mechanical damage to the active grill shutters or actuator caused by minor accidents or impacts with road debris
  • Failed or failing PCM or other control module, but note that since this is a rare event, the fault must be sought elsewhere before any control module is replaced or reprogrammed

What are the symptoms of code U11E9?

Some common symptoms of code P11E9 could include the following-

• Stored trouble code and possibly an illuminated warning light
• Depending on the nature of the problem, multiple additional trouble codes relating to the active grill shutters may be present along with P11E9
• The engine may overheat
• The transmission may overheat
• The A/C system might be deactivated
• The engine warm-up time may increase noticeably
• Fuel consumption may increase noticeably

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