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OBD Code U1120

Lost Communication with Air Suspension Module

CodeU1120
DescriptionLost Communication with Air Suspension Module
Possible CausesAir suspension module offline
SymptomsRide height control disabled|Rough ride
SystemNetwork

What Does U1120 Mean?

Lost Communication with Air Suspension Module. This diagnostic trouble code (DTC) is stored when the vehicle's onboard computer detects an issue with the network.

Code Breakdown

U = Network code

1 = Manufacturer-specific

How to Fix U1120

Follow these diagnostic steps to identify and resolve the issue. Always start with the simplest checks before moving to more involved repairs.

  1. Inspect suspension components for wear — bushings, ball joints, tie rods, and control arms.
  2. Check the ride height sensor (if equipped with electronic suspension) and its linkage.
  3. Inspect the air suspension compressor and air lines for leaks (if air suspension equipped).
  4. Test the electronic suspension control module and its connectors.
  5. Check for TSBs related to suspension component failures for your vehicle.
  6. Replace worn or failed components.
  7. Clear codes and test ride quality over bumps.

Note: These are general diagnostic guidelines. Some vehicles may have model-specific procedures. Always consult your vehicle's service manual for exact specifications and torque values. If you are not comfortable performing these steps, visit a qualified mechanic.

Frequently Asked Questions

Is U1120 serious?

Yes — U1120 is considered a high-severity code. You should have it diagnosed and repaired as soon as possible. Driving with this code active may cause further damage to your vehicle or pose a safety risk.

Can I clear U1120 myself?

You can clear any OBD-II code with a code scanner or by disconnecting the battery for 15-30 minutes. However, clearing the code without fixing the underlying problem will cause it to return — usually within one or two drive cycles. If the code triggered the check engine light, the light will come back on. Fix the root cause first, then clear the code.

How much does it cost to fix U1120?

Repair costs vary widely depending on the root cause. Some fixes are free (like tightening a gas cap) while others can cost several hundred dollars (like replacing a catalytic converter or oxygen sensor). A proper diagnosis with a professional scan tool — not just reading the code — is the first step to getting an accurate repair estimate. Many auto parts stores offer free code reading, but a thorough diagnosis usually requires a mechanic.

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