Diagnostic Trouble Code

DTC P0445 - EVAP Purge Control Circuit Fault

 

Features of the Circuit


The evaporative emission (EVAP) system comprises the following components:

  • Fuel tank.
  • EVAP vent solenoid.
  • Fuel pipes and hoses.
  • Fuel vapor lines.
  • Fuel cap.
  • EVAP canister.
  • Purge lines.
  • EVAP canister purge valve.
  • EVAP service port.

Further Details:

  • The evaporative emission system is probed by applying vacuum to the EVAP system and monitoring for a vacuum decay.
  •  The engine control module (ECM) monitors the vacuum level through the fuel tank pressure sensor signal.
  • The EVAP canister purge valve and the EVAP vent solenoid are turned on at the nick of time, allowing the engine to suck up a small vacuum on the entire EVAP system.
  •  After the requisite vacuum level has been obtained, the EVAP canister purge valve is switched OFF, locking the system entirely.
  •  If sufficient vacuum level cannot be derived, a large leak is indicated. This can be caused by the following conditions :

a)       Absent or tampered fuel cap.

b)       De-linked or faulty fuel tank pressure sensor.

c)       De-linked, damaged, pinched, or blocked EVAP purge line.

d)       De-linked or erroneous EVAP canister purge valve.

e)       De-linked or incorrect EVAP vent solenoid.

f)         Open ignition feed circuit to the EVAP vent or purge solenoid.

g)       Tampered EVAP canister.

h)       Leaking fuel sensor assembly O-ring.

i)         Leaking fuel tank or fuel filler beck.

Any of the above conditions can start DTC P0445.

  • The test is aborted if the tank vacuum is < 10 in H20 for 15 seconds and the manifold vacuum integral is > 49512 (proportional to purge mass from the tank).

 

Time for setting the DTC

Task boosted after DTC sets

When will DTC clear?

1) When the canister purge solenoid circuit is in a short to battery or short to ground state.

1) The Malfunction Indicator Lamp (MIL) will glow after three successive trips with a fail.

1) The MIL will turn off after four consecutive ignition cycles in which the diagnostic runs without a fault.

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2) The ECM will begin to store conditions which were present when the DTC failed.

 

2) Disconnecting the ECM battery feed for 10 seconds

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3) This information will be recorded in the Freeze Frame buffering Failure Records.

 

3) The scan tool can be used to remove all existing DTCs.

 

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4) A history DTC will be stored.

 

4) A history DTC will clear after 40 consecutive warm-up cycles without a fault.

       

Diagnostic Assistance

Although this DTC is considered a sort of type A diagnostic, it basically acts like a type B diagnostic under certain conditions. Whenever this diagnostic indicates the system has passed, or if the battery is disconnected, the diagnostic must fail twice before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately.

 Under this circumstance check for the following conditions:

  • Absent or tampered fuel cap.
  • Absent or tampered O-rings at fuel vapor and EVAP purge line canister fittings.
  • Cracked or punctured EVAP canister.
  • Damaged source vacuum line, EVAP purge line, EVAP vent hose or fuel tank vapor line.
  • Poor connection at the ECM. Inspect the harness connectors for the following conditions.
  • Backed-out terminals.
  • Improper mating.
  • Broken locks.
  • Improperly formed.
  • Damaged terminals.
  • Poor terminal-to-wire connection.
  • Damaged harness. Examine a) the wiring harness to the EVAP vent solenoid, b) EVAP canister purge valve and c) the fuel tank pressure sensor to ensure whether an intermittent open or short circuit prevails.
  • Kinked, pinched or plugged vacuum source, EVAP purge, or fuel tank vapor line. Ensure that the lines are not restricted.