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Home / DTC / P0AA2 — Hybrid/EV Battery Positive Contactor Circuit Stuck Open

P0AA2 — Hybrid/EV Battery Positive Contactor Circuit Stuck Open

Detailed page for trouble code P0AA2.

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Code

P0AA2

Generic P — Powertrain

Hybrid/EV Battery Positive Contactor Circuit Stuck Open

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Failed positive contactor (stuck or welded open)
  • Open or short in contactor control wiring or connectors
  • Faulty contactor driver or hybrid/HEV control module
  • Low 12V accessory battery or blown fuse/relay in contactor supply
  • Corroded terminals or poor ground
  • Interlock or safety circuit preventing contactor closure

Symptoms

  • Hybrid/EV system warning lamp or battery warning illuminated
  • Vehicle will not go into ready/drive mode, reduced propulsion or limp mode
  • Accessory or 12V systems may behave normally while HV is disabled
  • DTCs related to hybrid battery, contactors, or communications may also be present

What to check

  • Read all stored and pending codes and freeze-frame data from hybrid/HEV control module
  • Verify service interlocks (service plug/insulation monitor) are installed correctly and not open
  • Check 12 V battery voltage and related fuses/relays for the contactor circuit
  • Visually inspect contactor wiring, connectors and high-voltage connections for damage or corrosion
  • Do NOT touch high-voltage components unless qualified — observe manufacturer HV safety procedure

Signal parameters

  • Command signal from hybrid control module to contactor driver: typically a switched 12 V or ground drive; when commanded ON expect control output present (≈10–14 V or active ground depending on design)
  • Contactor coil resistance: typically low (a few ohms) — exact spec varies by vehicle; open circuit or very high resistance indicates coil failure
  • When commanded CLOSED, continuity should be present across the contactor high-voltage main terminals; when OPEN, there should be no continuity
  • Cranking/activation current: coil draw may be in the ampere range when energized; excessive or no current indicates fault
  • Status feedback (if equipped): ECU may show contactor state flag (OPEN/CLOSED) — should change to CLOSED within a defined time after command

Diagnostic algorithm

  1. Safety first: follow manufacturer high-voltage isolation procedure. Disable HV system, remove service plug or follow prescribed safety interlocks before touching high-voltage components.
  2. Scan tool: record freeze-frame and live data. Note if ECU commanded the contactor CLOSED and whether ECU reports the contactor as OPEN.
  3. Check 12V system: measure accessory battery voltage and inspect fuses/relays powering the contactor control circuit. Replace any blown fuses and retest.
  4. Visual inspection: examine wiring harness, terminals and connectors between hybrid control module and positive contactor for damage, looseness, corrosion or water intrusion.
  5. With HV isolated and service procedures followed, measure contactor coil resistance at the contactor connector. Compare to manufacturer spec. Open or very high resistance = failed coil.
  6. Reconnect 12V and, using a diagnostic tool or following safe procedures, command the contactor ON while monitoring coil supply voltage and coil current. Confirm control voltage appears at the contactor coil when commanded.
  7. If control voltage is present but contactor does not close, suspect mechanical failure of the contactor or internal fault; if control voltage is absent, trace back to the contactor driver, wiring, fuses and relays.
  8. Check for any safety interlocks (insulation monitoring, service plug position, HV fuse state) that could inhibit contactor operation. Resolve any interlock faults first.
  9. If wiring and coil are good but ECU driver does not output command, suspect hybrid control module or driver stage — verify module grounds and communications; consider module replacement only after verification.
  10. After repairs, clear codes and perform functional tests: command contactor open/close cycles, verify status changes in live data, and confirm no recurrence of P0AA2 during road test or HV cycling.

Likely causes

  • Open or corroded wiring at contactor connector
  • Failed contactor coil (no continuity or high resistance)
  • Contactor driver transistor or fuse blown in hybrid control unit
  • 12 V supply fuse or relay to contactor circuit blown
  • Safety interlock (HV interlock, service plug, insul. monitor) open

Fault status

⚠️ Status
Hybrid/EV battery positive contactor circuit reports stuck open — contactor failed to close when commanded. High-voltage battery remains disconnected.
🔴 Repair difficulty: Hard
⏱️ Diagnostic time: 1.5-4.0 hours

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Code

P0AA2

LAND ROVER P — Powertrain

The positive contactor circuit of the hybrid battery is stuck open The negative contactor circuit of the hybrid battery is stuck. The negative contactor circuit of the hybrid battery is stuck open

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Failed positive contactor (stuck or welded open)
  • Open or short in contactor control wiring or connectors
  • Faulty contactor driver or hybrid/HEV control module
  • Low 12V accessory battery or blown fuse/relay in contactor supply
  • Corroded terminals or poor ground
  • Interlock or safety circuit preventing contactor closure

Symptoms

  • Hybrid/EV system warning lamp or battery warning illuminated
  • Vehicle will not go into ready/drive mode, reduced propulsion or limp mode
  • Accessory or 12V systems may behave normally while HV is disabled
  • DTCs related to hybrid battery, contactors, or communications may also be present

What to check

  • Read all stored and pending codes and freeze-frame data from hybrid/HEV control module
  • Verify service interlocks (service plug/insulation monitor) are installed correctly and not open
  • Check 12 V battery voltage and related fuses/relays for the contactor circuit
  • Visually inspect contactor wiring, connectors and high-voltage connections for damage or corrosion
  • Do NOT touch high-voltage components unless qualified — observe manufacturer HV safety procedure

Signal parameters

  • Command signal from hybrid control module to contactor driver: typically a switched 12 V or ground drive; when commanded ON expect control output present (≈10–14 V or active ground depending on design)
  • Contactor coil resistance: typically low (a few ohms) — exact spec varies by vehicle; open circuit or very high resistance indicates coil failure
  • When commanded CLOSED, continuity should be present across the contactor high-voltage main terminals; when OPEN, there should be no continuity
  • Cranking/activation current: coil draw may be in the ampere range when energized; excessive or no current indicates fault
  • Status feedback (if equipped): ECU may show contactor state flag (OPEN/CLOSED) — should change to CLOSED within a defined time after command

Diagnostic algorithm

  1. Safety first: follow manufacturer high-voltage isolation procedure. Disable HV system, remove service plug or follow prescribed safety interlocks before touching high-voltage components.
  2. Scan tool: record freeze-frame and live data. Note if ECU commanded the contactor CLOSED and whether ECU reports the contactor as OPEN.
  3. Check 12V system: measure accessory battery voltage and inspect fuses/relays powering the contactor control circuit. Replace any blown fuses and retest.
  4. Visual inspection: examine wiring harness, terminals and connectors between hybrid control module and positive contactor for damage, looseness, corrosion or water intrusion.
  5. With HV isolated and service procedures followed, measure contactor coil resistance at the contactor connector. Compare to manufacturer spec. Open or very high resistance = failed coil.
  6. Reconnect 12V and, using a diagnostic tool or following safe procedures, command the contactor ON while monitoring coil supply voltage and coil current. Confirm control voltage appears at the contactor coil when commanded.
  7. If control voltage is present but contactor does not close, suspect mechanical failure of the contactor or internal fault; if control voltage is absent, trace back to the contactor driver, wiring, fuses and relays.
  8. Check for any safety interlocks (insulation monitoring, service plug position, HV fuse state) that could inhibit contactor operation. Resolve any interlock faults first.
  9. If wiring and coil are good but ECU driver does not output command, suspect hybrid control module or driver stage — verify module grounds and communications; consider module replacement only after verification.
  10. After repairs, clear codes and perform functional tests: command contactor open/close cycles, verify status changes in live data, and confirm no recurrence of P0AA2 during road test or HV cycling.

Likely causes

  • Open or corroded wiring at contactor connector
  • Failed contactor coil (no continuity or high resistance)
  • Contactor driver transistor or fuse blown in hybrid control unit
  • 12 V supply fuse or relay to contactor circuit blown
  • Safety interlock (HV interlock, service plug, insul. monitor) open

Fault status

⚠️ Status
Hybrid/EV battery positive contactor circuit reports stuck open — contactor failed to close when commanded. High-voltage battery remains disconnected.
🔴 Repair difficulty: Hard
⏱️ Diagnostic time: 1.5-4.0 hours

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P0AA0 P0AA1 P0AC0 U0100 U0121
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LAND ROVER

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