Troubleshooting P0446, P0441, P0455 & P0442 Trouble Codes:: Overview

A systematic approach to troubleshooting the mechanical aspects of the evaporative system is described below. The procedures below should be performed with HDS connected to monitor the system. All procedures described for a particular fault code should be performed to ensure system integrity. Due to emission systems integration, scanner code descriptions may be misleading. The repair sequence for vehicles with more than one code set is: 1st P0446; 2nd P0441; 3rd P0455; and 4th P0442. This means if P0455 and P0446 are both in the PCM memory, follow the procedures outlined in P0446 first, and then follow the procedures in P0455.

Note 1:
The procedure described below assumes that all electrical connections are in good condition. Repair all electrical related codes first [Canister Purge Valve (P0444,P0445), Canister Close Valve (P0447, P0448), DPS (P0451, P0452, P0453)].

Note 2:
A "test" hose should be made from a 20" length of 1/4" fuel hose to perform most of the diagnostic procedures.

Note 3:
One (or two) pair of hose pinching pliers (Snap-On P/N BLC2 or equivalent) will be needed to help troubleshoot the system.





I. P0446 is in the PCM memory, perform the following procedures. The HDS plot appears on Graph # 2.