Engine sign & Air con stop working unconditionally

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Vanne, Oct 27, 2015.

  1. Vanne

    Vanne Junior Member

    Aug 11, 2012
    Phnom Penh
    2005 Prius
    dear all my friends

    i have a problem with my car (prius 2004 ) just this morning , my car air con doesn't work without reason, it used to happen the same about half month ago but i just turn off the engine and turn it on many time it work as normal, and now it was happen again. and engine red icon also appear long time ago as well, when i ask technical guy to check it reply the code : pc 172 System too reach (....)
    please help me on this , thank in advance

  2. Patrick Wong

    Patrick Wong DIY Enthusiast

    Mar 8, 2008
    Green Valley, AZ
    2015 Prius
    Your car has two separate problems.

    The first problem is that your engine air/fuel mixture ratio is too rich, in other words there is a greater proportion of fuel than optimal. This is evidenced by DTC P0172. This could be due to a dirty mass air flow meter, a leaking injector, or perhaps a failing air/fuel ratio sensor.

    The second problem is with your air conditioning system. If it doesn't work, there always is a reason. I accept that reason may not be obvious to you. You need to have the system checked by someone competent to work on hybrid vehicles.

    The air conditioning system will be contaminated if equipment is utilized which had previously been used on regular vehicles. This is because the air conditioner compressor oil is very special for Toyota hybrids - it does not conduct electricity. Oil residue from other vehicles may contaminate your car's system.

    If there is no such person in your local area then you'll have to learn how to do that service yourself, and buy a set of manifold gauges and a vacuum pump. The system is probably low on refrigerant and the root cause will likely be due to a leak somewhere in the system.

    I would suggest if you DIY, you first recharge the system and add dye, to confirm that the system basically is operational. Then when it stops working again, look for the dye stain to figure out where the leak is, and replace the failed component.

    Subscribe to the Toyota repair manual website for information about how to do this, the correct high and low system pressures, etc. You may be able to subscribe to the Europe website.

    Toyota Service Information