CEL On, Help Please :p

[vanionBB]

I used AutoXray at my local Schucks and got the following codes:

P0420 Catalyst System Efficiency Below Threshold Bank 1
P0300 Random/Multiple Cylinder Misfire Detected

I have a 96 XLT with a 4.0 OHV engine. I have had this error before 2 times, and I cleared the codes each time hoping they would go away. They did not so I am stuck trying to figgure out what to do next.

I have replace the "easy to reach" oxygen sensor already, but this did not solve the problem. I think my next course would be to change the "hard to reach" oxygen sensor, unless someone has some ideas on what this might be.

Thanks in advance for any help

Cheers!

 

[jimbo74]

there should be more info than bank 1, especially on an obd2 vehicle......

it might be a sensor problem, a frayed wire, or a bad cat, also could be related to the misfire which is usually coil, plug or plug wire related

 

[ExplorerDMB]

since your misfire is random - I would suspect your CAT code to be the reason why the misfire is occuring!

-Drew

 

[churd69]

Stupid question, but did you do anything before the codes came on the first time? I had a friend who power washed under his hood before and pulled the code for random misfires. I would check your plugs and wires as mentioned above.

-Rich

 

[Runnin'OnEmpty]

IIRC, Ford has had a TSB out on the P0420 code. It seems that the PCM is too sensitive to changes between the before and after cat O2 sensors, and therefore triggers the cat efficiency code. Ford's cure is to reprogram the PCM. Be careful if you take it into a dealer though; many will want to replace the cat and O2s, (which will also fix it).