Hi everyone,

I’m wondering if someone can help me out with a suspension fault on a 2007 L322 with a hitachi air compressor. Replaced compressor and all valve blocks including passenger front height sensor. Car now has air and raised and Lowers when commanded. However, I’m still getting code C1A20-64 pressure increases too slowly. The compressor seems to pressurize the gallery just fine, shuts off, then purges and starts up again. It does this every so often then throws the code. While watching live data, I see pressure reach over 220 psi, then shut off. However I then see gallery pressure slowly drop to 190 psi and the compressor will then kick in again. Sometimes the compressor will shut off at 220 psi, purge to 40 psi and then start up again until it reaches 220 psi. Sometimes the compressor will purge back to 40 psi and remain off but I can see the pressure slowly INCREASE to about 44 psi, while compressor is OFF. It will then hold for a few mins and repeat the cycle by turning back on and going up to 220s psi. Until a suspension fault comes on. If I shut the car off and turn it back on, it allows me to raise and lower the car until it goes into suspension fault minutes later.



Compressor is aftermarket hitachi style.

Valve blocks are Arnott and so is the height sensor.



Car will not allow me to re calibrate the height sensor, it fails every time. Sometimes the air compressor runs while trying to calibrate, which I suspect may be the issue.



If I try to deflate the entire system and re inflate it tells me front height sensors are causing issues but if I force inflate, sensors start working fine.



I’ve checked for leaks in obvious places, but am confused as why pressure would increase (by 4 psi) in gallery if compressor is off and it purged right before. Where is the air coming from that the pressure sensor is reading? Is it something to worry about or is it no big deal as it only increases by 4 psi, not more.



Sometimes when compressor reaches 220psi it does not purge but instead pressure slowly drops until it kicks on again, sometimes it purges to 40 psi. Random occurrences with random psi. Not sure where to look next.



Any suggestions? Attaching live readings