2003 5.4L Engine Codes
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Junior Member
Joined: Apr 2011
Posts: 2
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2003 5.4L Engine Codes
P0303 #3 misfire
P0306 #6 engine misfire
P0171 system too lean bank 1
P0174 system too lean bank 2
motor has about 80k on it. I have reset the codes and they do come back. motor seems to run ok sometimes. has all standard maintenance.
I have replaced the DPFE sensor (code was set previously), checked vacume lines, cleaned MAF. I have the tools to trouble shoot this and my friend owns a mechanic shop. I just wanted to see if I coudl sort this out before I took it to him - he is doing it for parts, but I just wanted to see if I could tackle it first. Thanks for your help
P0306 #6 engine misfire
P0171 system too lean bank 1
P0174 system too lean bank 2
motor has about 80k on it. I have reset the codes and they do come back. motor seems to run ok sometimes. has all standard maintenance.
I have replaced the DPFE sensor (code was set previously), checked vacume lines, cleaned MAF. I have the tools to trouble shoot this and my friend owns a mechanic shop. I just wanted to see if I coudl sort this out before I took it to him - he is doing it for parts, but I just wanted to see if I could tackle it first. Thanks for your help
Senior Member
Joined: Oct 2010
Posts: 455
Likes: 22
For misfire, check plugs/wires/coils. You can replace plugs first round. See how plugs are from the misfire cylinder. Since the engine is only 80k, coils and wires can stay first round.
The lean code (both banks) is most like a vac leak downstream of MAF and upstream of intake manifold. It is not always easy to find the leak. Take advantage of your mechanic friend.
The lean code (both banks) is most like a vac leak downstream of MAF and upstream of intake manifold. It is not always easy to find the leak. Take advantage of your mechanic friend.