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DTC codes / P0Axx · Hybrid propulsion / P0AE6

P0AE6Hybrid/EV Battery Precharge Contactor A Control Circuit Low

P0AE6 indicates that the hybrid or electric vehicle battery pack's precharge contactor A control circuit is reporting a low-voltage condition, meaning the control module detects a short to ground or an open circuit on the command wire for that contactor. The precharge contactor is a relay that momentarily limits inrush current when connecting the high-voltage battery to the rest of the vehicle's electrical system, and a fault here prevents safe precharging.

SystemPowertrain
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the hybrid system warning light or service vehicle soon message
  • The vehicle may refuse to enter 'Ready' mode or start
  • A noticeable delay or failure when attempting to power on the high-voltage system
  • Audible clicking from the battery pack area may be absent during startup
  • Often no symptoms besides the warning light if the fault is intermittent

Common causes, most likely first

  1. Damaged or chafed wiring in the precharge contactor control circuit, causing a short to ground
  2. Corroded or loose electrical connector at the precharge contactor or battery control module
  3. Failed precharge contactor coil (open or shorted internally)
  4. Faulty battery control module or hybrid vehicle control module driver circuit
  5. Water intrusion or contamination in the battery pack connector area
  6. Aftermarket accessories improperly tapped into the control circuit

How to diagnose and fix it

  1. Perform a visual inspection of the precharge contactor control circuit wiring and connectors for damage, corrosion, or loose pins
  2. Use a scan tool to check for related codes and freeze-frame data, and verify the battery control module's commanded state for the precharge contactor
  3. Measure resistance of the precharge contactor coil and compare to specification to rule out an open or shorted coil
  4. Backprobe the control circuit at the contactor and at the control module to check for a short to ground or an open circuit with a multimeter
  5. If wiring and coil test good, substitute a known-good precharge contactor or control module to isolate the fault
  6. Repair or replace the faulty wiring, connector, contactor, or control module as needed, then clear codes and verify proper precharge operation

Precharge contactor faults that fool technicians

  • A low control circuit code often results from a short to ground in the wiring harness where it rubs against the battery pack frame, not from a failed contactor itself.
  • Intermittent codes can be caused by a loose connector pin that only loses contact when the vehicle is exposed to temperature swings or vibration.
  • Some vehicles set this code if the 12-volt auxiliary battery is weak, because the control module may not have enough voltage to properly drive the contactor coil.
  • The precharge contactor is sometimes part of a non-serviceable assembly, so technicians must verify the control circuit before condemning the entire battery pack.
  • A shorted precharge contactor coil can also set a high circuit code, so always check for both P0AE6 and its high-side counterpart when diagnosing.

Can I keep driving with P0AE6?

Do not continue driving with this code present, as the high-voltage system may not precharge correctly, leading to a no-start condition or potential damage to the contactors and inverter. Have the vehicle inspected by a qualified hybrid technician before attempting further operation.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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