P0AE5: Hybrid/EV Battery Precharge Contactor A Control Circuit Range/Performance

P0AE5 reports that the precharge function works electrically but does not deliver the expected result, so the controller judges the circuit implausible. Ford documents it in special service message SSM 47129: 2013-18 C-MAX and Fusion Hybrid and Energi models and the MKZ Hybrid may not start, with P0AE5 stored in the battery energy control module. When pinpoint tests show that the DC/DC converter, the cabin coolant heater or the A/C compressor has a low internal resistance on its high-voltage side, Ford replaces only that component, not the battery junction box. A load that drags the bus down keeps the precharge from reaching its target. Open, low and high driver faults are P0AE4, P0AE6 and P0AE7.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

Vehicle does not start or become ready
Red warning triangle or hybrid warning in the cluster
Possible additional codes from the faulty high-voltage consumer

Most likely causes

High-voltage consumer with low internal resistance (DC/DC converter, coolant heater, A/C compressor)
Precharge resistor degraded or wrong value
Precharge contactor responding slowly or with high contact resistance

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Compare the reading with other engine data while varying the engine speed.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

It can trigger limp mode.
It affects emissions.

What each character of P0AE5 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
A: Hybrid or air and fuel
E5: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0AE5?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0AE5?

The most common causes are: high-voltage consumer with low internal resistance (DC/DC converter, coolant heater, A/C compressor); precharge resistor degraded or wrong value; precharge contactor responding slowly or with high contact resistance.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.