18836/P2404/009220

18836/P2404/009220 - EVAP Leak Detection Pump Sense Circuit: Implausible Signal

Possible Symptoms

• Malfunction Indicator Light (MIL) ON

Possible Causes

• Faulty Leak Detection Pump (V144)
  • Electrical issue, fails ohm testing
  • Mechanical failure, fails vacuum testing
• Voltage supply problems to Leak Detection Pump (V144)
• Low or no vacuum supply to the Leak Detection Pump (V144)
• Evaporative Emission (EVAP) Canister System leaking pressure
• Faulty (N80) Evap purge solenoid

Possible Solutions

• Test Leak Detection Pump (V144) and it's wiring, see repair manual
  • Check voltage supply to Leak Detection Pump (V144) including J757 - Engine Component Power Supply Relay when applicable
• Test vacuum supply to Leak Detection Pump (V144) with engine at idle
• Pressure test Evaporative Emission (EVAP) Canister System for leaks, see repair manual
• Test (N80) Evap purge solenoid for leaking system pressure into the intake manifold

Special Notes

• If found on:
  • 2.0L BPY engine, see Technical Bulletin 20-07-13.
  • 2011 - 2014 Touareg 3.6L, see Tech Tip 20-13-04TT for possible coolant pump issue.
    • https://static.nhtsa.gov/odi/tsbs/2017/MC-10157825-9999.pdf NHSTA
• When found in VW/Audi models that use a J757 (Engine Component Power Supply Relay) to supply power to the Leak Detection Pump (V144), check the relay and power supply to V144 itself closely before replacing the pump. Faulty J757 relays often cause this DTC in the (4F) Audi A6.
• Case Study of P2404 due to no vacuum supply at the Leak Detection Pump (V144).