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SPN 4238 code for 2017 6.2

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Any one have similar problem?  Dealer can’t seem to clear out after trouble shooting and rest.  Keeps coming back after we hit the lake.

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That SPN code indicates a short term fuel trim error on bank 2 either running too rich or too lean (depending on the FMI code you are getting).

It can be caused by a faulty or loose O2 sensor, fuel pressure too high or low, a leaking or clogged or non functional fuel injector or harness plug , a vacuum or exhaust leak, even possibly a weak or no spark issue caused by a bad coil, wire, or spark plug, or even a faulty ECM or wiring harness.  Lots of stuff to check.

I always go for the easiest to check and repair first.  Swap the port O2 sensors with the starboard sensors, make sure they are all tight and the harness plugs are secure, run the boat and see if you get the same SPN 4238 code or if you get a SPN 4236 code instead.  If the code changes, you likely have a bad O2 sensor. 

If you still get the same SPN 4238 cods, check your fuel pressure and see if it is 55-62 PSI to confirm the engine is not running lean or rich.  Also, see if you can detect any vacuum or exhaust leaks or have a loose spark plug wire.

Edited by csleaver
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