code 42 questions

syclone#2659

syclone#2659

Donating Member
ok i have been having knock problems for a while now. so i unhooked the tan wire and set my timing -2 degrees, and then i hooked the tan wire back up. i also put in a new cap and rotor today. now i did a datamaster run, and the truck has little ore no knock and ran great but now i am now getting a code 42. also on the main data screen (datamaster) on top.it is saying data error and will flash red, durring the run. what do these thing mean i did a search and couldnt get any info, thanks
 
syclone#2659

syclone#2659

Donating Member
Re: code 42 questions

ive read in a few posts to try and set timing -2 if having problems with knock and see what happens there. my knock went down and at wot it never got above 1.7 and once the truck warmed up it read 0.0 so i will try and advance it a little soon to see what happens
 
SY2932

SY2932

Administrator
Re: code 42 questions

A code 42 centers around the EST wire, prolly just set the code in the ECM when you had the truck running to set the timing. Not uncommon for this code to be set because the truck has to run with the EST disconnected (open circuit). Removing the voltage to the ECM for at least 10 seconds should erase the code.
 
SY2932

SY2932

Administrator
Re: code 42 questions

BTW, if you are having to retard your timing to keep knock in check your fuel pump may be getting a little "tired" and/or your fuel filter may be due for replacement. Had the same problem in my daily driven S10 knocking even with 93 octane. Retarted the timing several times and that helped but, still experienced some. Few months later, fuel pump went out. Never been a problem since the new fuel pump was put in.
 
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