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DTC codes / BMW codes / P1445

P1445 · BMWDiagnostic Module Tank Leakage DM-TL Pump Control Circuit Signal Low

P1445 on BMW vehicles means the diagnostic module for tank leakage (DM-TL) has detected a low signal on the control circuit for its pump. The engine computer expects a certain voltage on the wire that commands the leak-detection pump to run, and it is seeing less than it should, so it flags the circuit as faulty.

SystemPowertrain
Code typeBMW specific
SeverityMedium
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • A slight fuel odor may be present if the leak pump has stopped running and the tank is not sealing properly.
  • In some cases, the engine may run slightly rough or have a minor hesitation if the fault interferes with evaporative system purging.
  • The remote fuel filler door release may not operate if the DM-TL module shares a circuit with the central locking system.
  • No driveability changes are typical, and many drivers continue to use the vehicle normally until inspection.

Common causes, most likely first

  1. A damaged or corroded wire in the DM-TL pump control circuit, often at the connector or where the harness passes near the fuel tank.
  2. A failed DM-TL pump or its integrated control module, which can short internally and pull the signal low.
  3. Poor electrical connection at the DM-TL module connector, including loose pins or water intrusion.
  4. A faulty engine control module (ECM) driver for that circuit, though this is less common than wiring or pump issues.
  5. A short to ground on the control wire between the ECM and the DM-TL pump, sometimes caused by chafing against the body or fuel tank shield.
  6. Low battery voltage or a weak ground connection at the DM-TL module, which can mimic a low signal on the control circuit.

How to diagnose and fix it

  1. Clear the code and test-drive the vehicle to see if P1445 returns; a one-time glitch may not reappear.
  2. Visually inspect the DM-TL pump connector and the wiring harness for corrosion, chafing, or loose pins, especially near the fuel tank.
  3. Measure the control circuit voltage at the DM-TL pump connector with a multimeter while commanding the pump on with a scan tool; compare to specifications.
  4. Check the ground circuit at the DM-TL module for excessive resistance using a voltage drop test.
  5. If the control signal is low at the pump but normal at the ECM, repair the wiring harness or replace the affected section.
  6. If the signal is low at the ECM with the pump disconnected, suspect the ECM driver and perform further pinpoint tests before replacement.
  7. Replace the DM-TL pump/module only after confirming the control circuit and ground are intact and the ECM is commanding the pump correctly.

What the DM-TL pump circuit really needs

  • The DM-TL pump is commanded by a pulse-width modulated signal, and a low signal can be set by a pump that draws too much current, not just by a wiring fault.
  • A common misdiagnosis is replacing the DM-TL pump when the real problem is a corroded connector pin that adds resistance and pulls the control voltage down.
  • The DM-TL module often shares a ground with the fuel level sensor or the fuel pump, so a bad ground can set P1445 without any issue in the pump itself.
  • On some BMW models, the DM-TL pump runs a self-test after refueling, so the code may only set after a fill-up and not during normal driving.
  • P1445 can be stored alongside fuel trim or EVAP codes if the leak pump failure affects the sealed fuel system, so always check for related codes before condemning the pump.

Can I keep driving with P1445?

You can usually continue driving with P1445 because it does not affect engine performance or safety, but avoid topping off the fuel tank and have the fault diagnosed soon to prevent a small evaporative leak from becoming a larger problem.

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 BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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