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Home / DTC / B12A3 — The steering column adjusts the engine actuation A

B12A3 — The steering column adjusts the engine actuation A

Detailed page for trouble code B12A3.

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Code

B12A3

LAND ROVER B — Body

The steering column adjusts the engine actuation A

Brand: LAND ROVER
Type: B — Body
Views: UK: 7 EN: 16 RU: 9
AI status
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Page language: EN

Causes

  • Loss or corruption of CAN/LIN messages between steering column module and engine/BCM/ABS modules
  • Faulty steering column module (SCM) or internal sensor (angle/torque/position)
  • Damaged wiring harness or poor connector contacts at the column or control modules
  • Low or unstable vehicle battery / supply voltage to modules
  • Software/configuration mismatch or missed calibration after module replacement
  • Intermittent mechanical fault in steering angle or torque sensors

Symptoms

  • Warning lamp(s) illuminated (engine, powertrain, ESC or steering warning)
  • Reduced engine torque or limp-home behavior when steering or during steering column adjustments
  • Erratic throttle response or engine idle changes correlated with steering position
  • Stored steering column / communication related DTCs alongside B12A3
  • Steering column adjustment (tilt/telescope) functions may be slow or unresponsive

What to check

  • Read full module memory with a dealer-level or capable scan tool; record all related DTCs and freeze frame data
  • Verify module presence on the bus (SCM, ECM/PCM, ABS, BCM) and check for lost-communication codes (U0xxx)
  • Inspect steering column connectors, pin retention, and wiring for corrosion, chafing or damage
  • Measure vehicle battery and charging system voltages under load and at rest
  • Check live-data for steering angle, torque sensor values, and engine actuation command while reproducing the symptom
  • Perform wiggle tests on harness/connectors while watching live data for drops or errors

Signal parameters

  • Steering angle sensor: reported as angle degrees (expect continuous values following wheel movement)
  • Steering torque sensor: reported as torque/force or as raw ADC (typically changes with driver input)
  • Engine actuation command: throttle/torque demand from SCM to ECM/PSM (reported as % or command value)
  • Bus electrical: CAN dominant/recessive voltages ~1–3.5V typical (verify with scope), nominal battery ~12V
  • Message frequency: steering-related CAN messages typically tens of Hz (verify expected rate with OEM data)

Diagnostic algorithm

  1. Connect a capable scan tool and retrieve all DTCs from SCM, ECM/PCM, ABS and BCM. Note timestamps and freeze frame data.
  2. Clear codes, attempt to reproduce the fault condition while monitoring live data streams: steering angle, torque sensor, engine actuation command, bus status.
  3. Verify module communication: confirm SCM appears on the network and compare live message rates to expected values. Log any lost-communication codes.
  4. Inspect physical wiring and connectors at the steering column for damage, corrosion or loose pins. Repair or reseat as required.
  5. Measure supply and ground voltages at the steering column module with ignition on and during repro. Confirm stable 12V and good ground.
  6. Perform wiggle tests on harness and connectors while watching for data dropouts or DTCs reappearing.
  7. If wiring and supply are good, check for available software/firmware updates and perform module reprogramming or calibration procedures per OEM service information.
  8. If problem persists, swap in a known-good SCM (if available) or bench-test the suspect module per manufacturer procedures.
  9. After repair or module replacement, clear codes and verify fault does not return during road test and across operating conditions.
  10. If no root cause is found, escalate to manufacturer technical support and check for technical service bulletins (TSBs).

Likely causes

  • Open/short or high-resistance wiring at steering column connector
  • Steering column module firmware bug or corrupted configuration
  • CAN bus fault (short to battery/ground or high bus load) preventing valid engine-actuation messages
  • Failed steering torque/angle sensor within the column
  • Transient low voltage event (battery weak or charging system issue)

Fault status

⚠️ Status
Steering column adjustment affecting engine actuation A — communication or sensor fault detected.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

B12A0 B12A1 B12A2 B12A4 U0100 U0415
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