Rick's Free Auto Repair Advice

P0AA6 Prius No Start

P0AA6 Prius No Start

What the P0AA6 code is all about

The Toyota power management control ECU monitors the insulation resistance between the high voltage circuits and body. If the insulation resistance decreases, the power management control ECU stores a trouble code P0AA6 along with a detail information code suffix. Most inexpensive scan tools don’t read the detail code suffix and without the suffix, you really don’t know where to start your diagnostic.

P0AA6 information suffix detail codes

P0AA6 -526 The insulation resistance between the high-voltage circuit and the body has decreased
P0AA6 -611 The insulation resistance of the compressor with motor assembly or air conditioning inverter has decreased.
P0AA6 -612 The insulation resistance of the HV battery, battery smart unit, SMR or SMRG has decreased.
P0AA6 -613 The insulation resistance of the hybrid vehicle transaxle assembly orinverter for generator (MG1) and motor (MG2) has decreased.
P0AA6 -614 The insulation resistance of the inverter for generator (MG1) and motor(MG2), A/C inverter, SMR, SMRG or frame wire has decreased.

The codes mean that there’s a high voltage leak somewhere in the vehicle. A P0AA6 -612 High voltage leak, for example can mean that a module in the high voltage battery has a fissue and is leaking electrolyte, causing a short circuit to the metal case. That would require a rebuilt HV battery pack.

A P0AA6 -611, on the other hand can mean that a recent AC repair was done improperly. The AC compressor in the Prius requires a special non-conductive oil. If the wrong oil was used, this code can appear.

Diagnostics you can do to fix P0AA6 Prius No Start

Almost all the tests for a P0AA6 code require special equipment. However, a failure in your 12-volt starting battery can generate this code, especially if there’s a short between cells. You don’t need special equipment to test your 12-volt starting battery.

Start by checking starting battery voltage using a multimeter. Connect the probes directly to the battery posts, not the battery terminals. Battery voltage must be as least 12.2 volts or more. If the voltage is lower than 12.2 volts, it is severely discharged. Charge the battery and retest. If it still shows low voltage, replace it.

If the voltage is below 10-volts, chances are high that you have at least one shorted cell in the starting battery and that will set a P0AA6 code. If the battery won’t accept and hold a charge, replace it.

If the P0AA6 occurred right after an AC recharge, you or the shop may have used the wrong refrigerant oil. In that case, the system must be evacuated, the compressor replaced and the entire system flushed to remove the wrong oil.

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Posted on by Rick Muscoplat



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