šØ Diagnostic Profile
Vehicle Make: BMW
Technical Description: Leakage Diagnostic Pump Control Circuit Signal High
This fault code indicates that the Evaporative Emissions (EVAP) Leakage Diagnostic Module (LDM) or DMTL (Diagnostic Module Tank Leakage) pump is reporting a control circuit signal that is higher in voltage than expected. This typically points toward a wiring issue, a faulty pump, or a blockage within the EVAP system causing the pump to work incorrectly and send an abnormal electrical signal back to the DME/DDE (engine control module).
šØ Repair Difficulty Tier
Difficulty Rating: Intermediate
This repair requires a diagnostic scan tool capable of reading live EVAP system data (BMW ISTA or equivalent OBD2 scanner with manufacturer-specific PIDs) along with a multimeter to test circuit continuity and voltage levels. While not requiring complex module programming in most cases, it does require knowledge of vacuum/pressure systems and electrical diagnostics. No airbag or restraint systems are involved, keeping liability relatively low.
š ļø Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the Diagnostic Module Tank Leakage (DMTL) pump located near the charcoal canister, typically under the rear of the vehicle near the fuel tank. Check the electrical connector for corrosion, bent pins, or loose connections. Inspect the wiring harness leading to the pump for chafing, rodent damage, or melted insulation. Additionally, examine the vacuum/vent lines connected to the pump for cracks, disconnections, or blockages caused by debris or insects, as a blocked line can cause the pump to overwork and trigger a high signal fault.
Step 2: Diagnostic Verification
Connect a BMW-specific scan tool (such as ISTA/D) or a quality OBD2 scanner capable of reading manufacturer-specific live data. Navigate to the EVAP system tests and activate the DMTL pump test routine to observe real-time pump behavior. Using a multimeter, backprobe the control circuit wire at the pump connector and check for voltage readings while the pump is commanded on and off by the module ā a reading significantly higher than the expected reference voltage (often 0.5Vā4.5V range depending on circuit design) confirms a ‘Signal High’ condition. Also test the ground circuit for excessive resistance, as a poor ground can falsely elevate signal voltage.
Step 3: Resolution & Reset Process
If wiring and connectors test fine but the pump still shows abnormal signal behavior, replace the DMTL/Leakage Diagnostic Pump assembly as it is often a sealed unit that cannot be repaired internally. After replacement, clear the stored fault codes using the scan tool. Perform a forced EVAP system leak test through the scan tool’s special functions menu to confirm the new pump cycles correctly and that no leaks are present in the tank, lines, or canister. Complete a drive cycle to allow the DME/DDE to verify the EVAP monitor has run successfully and confirm the fault does not return.
š¦ Parts, Labor, and Budget Estimates
Required Components/Software: DMTL/Leakage Diagnostic Pump assembly, EVAP system vacuum hoses/seals (if damaged), BMW ISTA diagnostic software or equivalent scan tool with live data capability, digital multimeter.
Average Component Price: $150 – $350 for OEM or quality aftermarket DMTL pump; additional $20-$50 if hoses or connectors need replacement.
Estimated Labor Hours: 0.5 – 1.5 hours for diagnosis, plus 0.5 – 1.0 hour for pump replacement and system verification (total estimated shop time: 1.0 – 2.5 hours).