Help! 2002 jeep liberty 3.7 *** P0201

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AdrianeWest

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I have a 2002 jeep liberty 3.7 and it was running fine until it wasn’t. It has stranded me multiple times we’ve been getting codes for sensors, the O2 sensors And a leak which it’s always had. We’ve replaced tons of sensors, check the battery, all new plugs and all new spark plugs and yes, they were correctly gapped, all new O2 sensors. All fluids have been checked. Oil changed has also been done. Leading up to this, we were having issues starting, but it wasn’t every single time. it would crank, but sometimes you would have to feather the gas for it to actually start. A lot of times she start right up no problems. I drove to town the other night had to make a pitstop and up until then she was running great no issues no problems. Nothing. she didn’t start when she did start she wouldn’t stay running and kept wanting to die and wouldn’t idle. Everything has been replaced that I mentioned above and it seemed like it did nothing and now we’re getting the code P0201 for injector one control circuit. we’re at our wits end and this is our only vehicle. I’ve already had to miss work because of this and we just don’t know what else to do. if anybody has had this happen or knows anything that could help us I would so greatly appreciate it.
 

mrlavalamp

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My first guess based on what you have already done is wiring harness. Vehicles that age round these parts start having wiring problems all the time. Its hot and dry here and with 20+ years of thermal cycling and the wire insulation/plastic connectors start to fail, many have lost their seals or had wires pull out some so corrosion sets in too. I would start by checking connections on the wiring harness and looking at the contacts for corrosion. Use contact cleaner and dielectric grease to keep moisture out once it is cleaned up.

If you do need to repair wires, crimp on connectors will get you around but you should replace them with soldered connections asap, especially on anything that sends or receives a signal, the crimp connectors just add too much resistance to the circuit and they often wont function correctly as a result. A full harness replacement might be the best course if you find multiple problems as at that point you will just be repairing different parts over and over as it continues to fail.
 

gvaldez

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Others on the forum will have more experience on this but if you've not already done so, start by testing the injector and the wiring to it. A faulty injector will likely cause rough idle and misfires. There are other possibilities but this is where I started when I had a similar code on my 02.
 

dtennes

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Any chance a mechanic has recently replaced injector #2? If "yes" and the replaced injector is not either a true new-in-sealed-box Mopar or Bosch part... then its probably a garbage aftermarket (or "rebuilt") injector will generally go bad after a couple of weeks/months.
 

AdrianeWest

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Others on the forum will have more experience on this but if you've not already done so, start by testing the injector and the wiring to it. A faulty injector will likely cause rough idle and misfires. There are other possibilities but this is where I started when I had a similar code on my 02.
We just tested the injectors tonight and all of them check out in our firing and working as they should. We are definitely going to try checking all the connectors again in cleaning and using the grease tho. It’s really got us thrown for a loop at this point.
 

AdrianeWest

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Any chance a mechanic has recently replaced injector #2? If "yes" and the replaced injector is not either a true new-in-sealed-box Mopar or Bosch part... then its probably a garbage aftermarket (or "rebuilt") injector will generally go bad after a couple of weeks/months.
We just had all the injectors tested and they all checked out and are working as should. Everything is original on this jeep besides what we’ve replaced.
 
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