How to Fix Air Suspension Issues in the Peugeot Boxer? (7+ Troubleshooting Tips)

In this brief article, we are going to discuss the Peugeot Boxer air Suspension problems, what the causes are, and Troubleshooting Tips to help DIY enthusiasts save on repair costs.

Most common air suspension issues in the Peugeot Boxer

The most common air suspension issues seen in the Peugeot Boxer is:

  • Rear Suspension Sagging

What suspension does the Peugeot Boxer have?

The Peugeot Boxer is the second generation of the Fiat Ducato Utility Van, originally developed by Stellantis. The Boxer has been on sale since 1994. The Fiat Ducato has been marketed by multiple Auto manufacturers under the names Citroën Jumper and Ram ProMaster

Rear Suspension

The Peugeot Boxer has a Trailing axle with Air springs and shock absorbers, Anti Roll bar and a Panhard Rod. The air suspension is height adjustable and particularly useful during loading and unloading.

The Air suspension has a separate Electronic control unit (ECU) called CAAR located in the engine compartment. The standard system has a Compressor, 2 rear ride-height sensors and 2 rear air springs.

An optional Manual Ride height control (CAM) is available that provides a manual ride height adjustment button inside the cabin at the rear tailgate and an air reservoir.

(1) Anti-roll bar

(2) right-hand pneumatic spring

(3) Heel bump stop

(4) Air compressor filter

(5) left-hand pneumatic spring

(6) damper

(7) Compressed air reservoir

(8) Air compressor along with 4 solenoid valves (there is no separate Valve Block for this system)

(9) Body height sensor

(10) Panhard Rod

(11) Rear Trailing axle

The CAAR receives input signals from:

  • The Ride height sensors
  • The Compressor Pressure sensor
  • The compressor temperature sensor
  • System inhibit requests
  • Manual requests

to either raise or lower the vehicle.

Raising the Suspension

If the height sensors detect that the rear ride height is less than the nominal ride height, the CAAR signals the compressor to start, and the 2 air spring solenoids to open. The compressor pressurizes the air springs until the nominal ride height is detected.

Lowering the Suspension

From the ‘Raised’ condition, when lowering the suspension, the Compressor opens its exhaust solenoid valve and the 2 air Spring solenoid valves to let out air and lower the ride height until the nominal ride height is achieved.

Rear Suspension Sagging


  • Rear Bump Stops hitting often during normal driving
  • Rear suspension sits low when parked

Root Causes for Peugeot Boxer Rear Suspension Sagging

  • The cause of the problem is the Peugeot Boxer rear air suspension system
  • The system is not inflating the Air Springs and therefore causing the rear-side of the body to sag
  • The potential causes for this type of failure would be:
    • Ride height sensor malfunction
    • Leakage in the Air Springs
    • Compressor malfunction

Troubleshooting Rear Suspension Sagging: Ride height sensor malfunction

  • The Ride height sensor provides a signal to the CAAR Control unit as to the actual ride height
  • The system, ideally, would signal the compressor to pressurize the air springs in order to match the nominal ride height
  • When the sensor malfunctions, signals to the CAAR system get disrupted, causing a low ride height at the rear suspension
  • First check for electrical continuity at the sensor terminals to eliminate any possible wiring problem
  • If the wiring is found to be OK then the sensor would have to be replaced

Troubleshooting Rear Suspension Sagging: Leakage in the Air Springs

  • Within the Air suspension, the Air Springs are the most vulnerable to failure, as they are made of reinforced rubber and they undergo the maximum wear and tear during vehicle operation
  • Over time, the Air springs develop cracks and form holes through which air escapes
  • A minor leak in the air spring causes the compressor to run for longer periods because of the frequent falling of ride height. If left unattended, this could cause the compressor to overheat and seize.
  • Apart from the air spring itself, the air spring air connector O-Rings could wear out, causing air leakages
  • All leakages must be located using the Soapy Bubble Test.

Soapy Bubble Leakage Test

  • This is the same procedure to detect and fix a Tire puncture
  • Fill a Spray can with Soapy water in a 50:50 proportion
  • Spray the soapy solution on all the air suspension points where leakage is suspected
  • Observe for Bubbles that form persistently at a particular spot even after you try wiping the foam with a finger
  • These persistent bubble spots are the leakage locations
  • While replacing the Air spring, it must be depressurized using the Diagnostic Scan tool Depressurization function

Troubleshooting Rear Suspension Sagging: Compressor malfunction

  • The compressor is responsible for developing the required pressure at the Air Springs.
  • If the compressor is not able to develop the required pressure, the rear suspension will sag
  • First, check if you hear the compressor noise when you start the vehicle
  • If the noise is heard, then the compressor may not be able to generate the required pressure (~4 bar) at the air springs
  • This can be verified using a diagnostic tool and measuring live data while the vehicle and compressor are both running. Look for the Pressure sensor reading to see whether it is below 4 bar
  • If the pressure reads below the operating pressure, then it could be a fault with either the compressor, the desiccator, or any of the valves
  • Before Diagnosing the valves, the valves outlet connectors can first be checked for leakage by spraying soapy water solution
  • Valve operation can also be diagnosed using the diagnostic tests available in the diagnostic scanner. Test each of the valves using the available operation tests.
  • If the solenoid valves are found to be functioning OK, then the next thing is to check the desiccator
  • The desiccator contains desiccant pellets that should ideally be blue in color. The desiccant expands and turns brown when totally saturated. When the desiccant is saturated, it restricts the flow of air from the compressor to the valves. The desiccant can be replaced during compressor rebuild.
  • If either the desiccant replacement did not help, and/or if the solenoid valves are faulty then the compressor needs to be Rebuilt or replaced.

Replacing / Rebuilding the Air Compressor

  • Although there are rebuild kits available for the compressor, replacement would be the most ideal solution.
  • Rebuild kits would usually contain the Teflon Piston rings, Retainer Springs and O-rings required to restore the compressor’s capability to seal air.


In this brief article, we are going to discuss the Peugeot Boxer air Suspension problems, what the causes are, and Troubleshooting Tips to help DIY enthusiasts save on repair costs.

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