Error code P2181

[Teligence]

I have an active P2181 with a pending P0128. No change in either status since the Fault light lit.
1. I replaced the thermostat with a new tested one that maintains the prescribed temp (195F).
2. I've replaced the ECT sensor with a new one.
3. I've fully drained (including the block), flushed, refilled, and have run/driven it at NOT (Normal Operating Temperature) for over 40 minutes.
4. The displayed temperature on the dash shows just slightly under the center mark - about where I'd expect for a 195F t-stat. My bluetooth scanner shows that when idling, the temp settles at 195.8F, so, the ECT is sending an acceptable temp to the PCM.
5. After several warmups/cooldowns, the coolant level is still good (just above the cold fill line after the engine has cooled to ambient.

So, I'm at a loss at this point. Any suggestions other than taking it to a shop where they'll probably want to do exactly what I've already done?

 

[Smokeybear01]

You don't mention it so I'm going to ask-did you clear the codes since doing all the work?

 

[Teligence]

Just an update as to the fix:
1. The codes wouldn't clear using a scanner, so I found out that some codes can't be simply cleared by a scan tool as long as a qualifying condition remains.
2. As a quick and easy attempt (even though with an expectation that it wouldn't work) I disconnected the battery and shorted the 2 connectors (NOT the battery terminals!) to drain any stored capacitance, and left the battery disconnected for over 30 minutes. No change.
3. Finally, what DID work was disconnecting all 4 connectors from the PCM, then reconnecting them once they were all connected.

It seems that there might have been a marginal connection in a related pin that threw an erroneous "condition" that caused the error codes. I re-ran the fault scan and came up clean. Even after over 100 miles which included several full warm-up/cooldown cycles, no codes - not even pending.

So, before spending hard-earned $$$ of parts or service, just try a (not-so-simple) disconnect/reconnect on related components on the outside chance that connections just need to be reseated.