i get the 1211 most of the time when in stock mode driving normal for years now. truck seems to run fine. read about unplugging the icp and checking idle. is this necessary? is the icp the main reason for the p1211? tired of ses light coming on, thanks

 

You get the light in stock mode? What about in a light tune mode? With the lift and mods, perhaps you're better off running a light tune to help the torque curve along.

 

Yea only in stock. The other mode is 60hp tow. Dp chip doesn't let the 1211 come up

 

I'm doubting the code/SES light is triggered while you are idling. If it did, you would see the idle get rough or change drastically. So unplugging the ICP sensor is not going to help you diagnose anything.


Now if you had a problem idling, then yes that might help you track down what is going on.


Realistically you'll probably have to datalog what is happening while driving.

 

There are two times a P1211 will illuminate the SES.

1. If set during normal engine operation, indicates engine is operating in open loop control and injection control pressure is above or below desired pressure (see photo for testing). The best way to attack this is by performing some simple tests. Of course a Breakout Box makes it easier. But, a simple check of the connectors, check for damaged pins, corrosion, loose terminals, etc. Normally, I would replace the IPR with a known good one if no obvious connection issues were present. But, since you've seen this over history and not with a Tune, a bad connection is perhaps the best place to begin.

2. If set during KOER test, indicates ICP system failed step test and could not maintain commanded pressure.

P1211 indicates that injection control pressure was above or below commanded "desired" pressure during self test mode. So, unplugging it will result is test failure during the test mode.

1. Possible causes: (I marked these what "I" think the likely cause "may" be.
a. incorrect oil or viscosity (not likely)
b. poor oil quality (not likely)
c. gel fuel/no fuel (not likely)
d. low fuel pressure (Possible)
e. damaged IPR valve (Possible)
f. high-pressure oil system leak (Possible)
g. damaged high-pressure oil pump (Possible)
h. damaged PCM (not likely)

I would recommend, just for fun, verify correct oil quality/viscosity and correct fuel grade are being used for the temperature conditions.

If you have access to a Scan Tool, you should monitor these inputs, paying primary attention to the DC (%) of the IPR.

ICP 500 PSI or 3.4 MPAM Minimum
ICPv (KOEO) Spec 0.20v - 0.30v
FUEL PW: 1 MS - 6 MS ( <1 / >6 IDM Suspect)
DC% - Cranking NTE 20% / 65% is Closed. (IPR Suspect)
ICP - A minimum of 500 PSI

 

thank you for that

 

There are possible causes that I didn't see on the list, but they apply to tuned trucks. A "hot" tune will force even a healthy engine into a condition it can't sustain, or a tired HPOP that works fine in stock tune falls flat with the higher demand of an elevated HP.

The other possibility not on the list is a "lying" ICP sensor. This one is frighteningly common at our age of truck. The "signature" of a bad ICP sensor is a crazy-low IPR command for a given ICP reading.