Emissions - DTC P1457 Possible Clogged Line

SOURCE:
Honda Service News July 2004

TITLE:
Got DTC P1457? Check for a Clogged EVAP Canister Purge Line.

APPLIES TO:
2002-03 CR-V

SERVICE TIP:
Got a DTC P1457 [EVAP control system leakage (EVAP canister system)]? The problem could be a clogged EVAP canister purge line. If your customer was out four-wheeling it, there's a good possibility that mud, sand, or debris could have been sucked into the line, especially if the EVAP canister got damaged or ripped from the vehicle or if the vehicle was plowing through some deep,
standing water.

A clogged EVAP canister purge line can delay the supply of vacuum to the fuel tank pressure (FTP) sensor. If the FTP sensor reacts sluggishly, the voltage won't drop down fast enough, and the ECM/PCM will set a DTC P1457 and maybe a test ID (TID) 2D.

To check for a clogged EVAP canister purge line, connect the HDS with version 1.012.023 or later software to the 16P DLC, and run the EVAP System Function Test. If the EVAP system fails the test, you'll need to troubleshoot and repair the problem. If the EVAP system passes the test, then follow these steps to check for a clog in the purge line from the EVAP canister to the engine:

1. Disconnect the purge hose at the EVAP canister, and attach a vacuum gauge to the hose.

2. Start the engine, and activate the purge control valve by back-probing and grounding the YEL/BLU wire. Watch the vacuum gauge.

- If the gauge needle instantly reads the manifold vacuum, then the purge valve is clear. Reconnect the purge hose to the EVAP canister, and look for other possible causes.

- If the gauge needle doesn't instantly read the manifold vacuum, then the purge control valve could be clogged. Go to step 3.

3. Disconnect the hose between the EVAP test port and the purge control valve. Attach a vacuum gauge to the test port end of the hose.

4. Activate the purge control valve by backprobing and grounding the YEL/BLU wire. Watch the vacuum gauge.

- If the gauge needle instantly reads the manifold vacuum, then clean or replace the EVAP test port, the purge line to the rear of the vehicle, or both.

- If the gauge needle doesn't instantly read the manifold vacuum, then look for a clogged purge control valve port in the intake manifold. If the port is clear, then replace the purge control valve, and retest.