How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Chris Your Own Question
Chris, Shop Foreman
Category: Dodge
Satisfied Customers: 13859
Experience:  Dodge/Cummins and Chrysler Certified Master Tech
Type Your Dodge Question Here...
Chris is online now
A new question is answered every 9 seconds

Have a 03 dodge 2500 5.9 cummings code p0602 replaced ecm 6

This answer was rated:

have a 03 dodge 2500 5.9 cummings code p0602 replaced ecm 6 times all dodge ecms with flash to match vin. all power and grounds are good. replaced engine harness new from dodge. new alt new battery's "votage spikes". had dash out looked over all the wiring it all checked out, pulled bed and inspected wiring and tested it all checked out. we have had every harness out and checked every connector still is killing the ecus.
JA: Have you checked all the fuses? Do you have a wiring diagram?
Customer: fuses are good relays are good ect. yes we have shopkey pro .
JA: Are you fixing your B2500 yourself? What have you tried so far?
Customer: we at the shop are fixing it. replaced ecms, harness's, checked every wire with a dmm and visual.
JA: Anything else you want the mechanic to know before I connect you?
Customer: we have tried every thing we can think of

Hello, my name is ***** ***** I will assist you today. Besides the code, are you noticing any performance issues?


Customer: replied 7 months ago.
no sir but on decal it will die. and if it idel's to long the rpms will dip then the truck will rev up then completely die

Ok, I have found a Chrysler Star case that talks about this code. I think you have a fuel/injector issue and not so much an electrical problem. Read this bulletin I found:


Case NumberK13104246

Vehicle Issue-P0602 Typically there is a driveability concern such as low power, hard start or no start concern, etc...;The ECM may have been recently flash updated and / or replaced.

System or ComponentDTC / Error Message;ECM

Recommendation: P0602 is generally an erroneous fault code, disregard the P0602 fault. Perform fuel system flow tests, reference TSB 14-03-06 revision A to diagnose the original engine performance problem.

Modification Date09/30/08 8:42 PM

I can also send you the TSB mentioned above.


Here is the TSB in that link below. Click on it to see it. Hopefully this helps!


Customer: replied 7 months ago.
wile driving it will be fine then on my scanner as soon as the code comes up there is no throttle response and if you let off the pedel it will die. or if you push the clutch in while down shifting "so lets say your in 6th and let off the throttle and push in the clutch it will die". or if you trucker shift "rev match" the down shift it wont die untell about 5mph 1k rpm at a cost "no clutch at all while down shifting then 1k and it will die. ill look at the tsb righ now.

Any after market items on the truck?

Customer: replied 7 months ago.
we installed a fass fuel system and pressure to the high pressure pump is really good. on my scan tool the high pressure pump passes for psi. injectors are new aswell. but we installed the fass after the truck came in with the first ecu and the code. to see if it would resolve the problem.

Okay, well if you pull up the code diagnostics, it says ECM or "flash ECM". You have replaced it 6 times, and I don't think this is an ECM at this point. I recommend performing injector flow/return tests. One of those injectors may be returning too much fuel, or you may have an injector pump/FCA issue when the engine temperature gets up there. Time to check the fuel system next.


Customer: replied 7 months ago.
that is weird you say that now. because it will be fine untell it gets to temp. then the problems will start

Just thinking "outside the box" so to speak. Knowing that makes me think that it is not electrical.


Customer: replied 7 months ago.
I agree we needed some outside thought on this ill ckeck what I can hear at the shop and have the injectors sent out for testing.

Sounds good. I think that is the best move. Ignore the code for now and treat this like a performance issue with no codes.


Chris and 4 other Dodge Specialists are ready to help you
Customer: replied 7 months ago.
will do thank you very much

You are very welcome and thank you for the positive rating! I will keep this post open for a few weeks just in case you have any follow up questions.


Customer: replied 7 months ago.
hello this is Zach I own the shop this truck is being repaired at. initially this truck was bought in Utah, while driving to Idaho the CEL came on and the owner dropped it off at my shop. code was APPS voltage high, no big deal did the flow chart step 2 was replace sensor, replaced sensor code still present. took truck to dodge for ecm flash, flash did nothing. recommended new ecm. got truck back to the shop and dug around a little, in the back seat was a paper with a sales pitch, new tires, new b&w ball..... NEW ECM. called the previous owner. they informed me that was the same code they had when they had the ecm replace right before they sold it. luckily the ecm had warranty we figured we would warranty it out problem solved right. Wrong, had the ecm warranty'd put it on now we had a fueling calibration error. had a local shop flash the ecm with no positive outcome. recommended ecm replacement again off the flow chart. got an ecm out of junk yard Dodge oem numbers! thought maybe this aftermarket ecm company was a joke. wrong again after having vin flashed into ecm back to apps voltage high code. pulled harness checked truck front to back repaired all questionable connections rubs...... replaced fca, crank sensor, cam sensor, fuel rail pressure sensor, alternator, same results, ordered used engine harness, new ecm, pulled dash inspected every inch of wire everywhere. new ecm throws fueling calibration error 602 and number 6 injector fires improperly. installed new pass over connectors to injectors ohmed all wires for short to power or ground. nothing test bad same results. ive seen some crazy things on trucks but this takes the cake. why will an ecm swap change the code from fueling calibration error to apps voltage high. I don't think its injectors but ive been wrong in the past. I have a set available and on the way for tomorrow. also have a new cp3 off a 2005 on my pickup. will the cp3 interchange? I know injectors will not because the spray angle on the nozzles.
This is indeeda good one huh? The 2005 injection pump should be ok to swap onto the 2003. They are the same. Get those injectors checked and get back to me.Chris
Customer: replied 7 months ago.
the fca voltage drops and is relating it to the rail pressure to drop tell it dies.

That would make sense. Does it do that with the other ECM's?

Customer: replied 7 months ago.
yup everyone

And you have replaced the engine harness correct?

Customer: replied 7 months ago.
we have
Ok, let me research this some more and get back to you.

Have you tried swapping the CP3 pump yet?

Customer: replied 6 months ago.
if the driver is losing power we don't see how changing the pump will change it.

True. Tell me if you disconnect the connector at the FCA while the rail pressure starts to drop, will the pressure come back up?

Customer: replied 6 months ago.
ill check that when we pull the truck back in.