# 2003 Chevy S10 4.3L Vortec V6



## GZ (Jan 31, 2010)

Just want confirmation or ideas.

I am helping a co-worker/friend with his truck.

2003 Chevy S10 4.3L Vortec V6

His vehicle is showing a check-engine light, so I used my handheld scanner to pull the codes.

p0101 - MAF out of range
p0341 - CPS out of range
p0420 - Catalytic system efficiency
Pending - p0420


The first two lead me to believe he has a timing problem... Possibly a slipped timing belt/chain.

Could this situation cause p0420 or is it likely he will need to replace his Catalytic converter?

Any other ideas on what may be the cause, please share.

Here is some additional info... He says that the truck runs alright. The engine sounds strong and smooth when idling and there are no audible misses. Unfortunately I only had a couple minutes to take a look and couldn't dig any deeper.


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## octaneman (May 13, 2009)

The out of range codes mean that the frequency at which the sensors run have passed their limit. The computer registers how many times the engine is turned on/off, after it reaches a specific limit ( usually 40 times), the computer memory will automatically re-set to the last best settings even if it has registered codes. The problem is not related to the normal stuff, plugs, wires etc.. Sensors that are exposed to the elements get dirty and send mixed signals to the computer. Cleaning out the mass air flow is where you should start first, remove it and then using alcohol and Q-tip clear the debris inside. Do not use solvents or you will destroy the sensor. Move on to the crank sensor and clear any debris that the magnetic tip has accumulated, as for the MAP sensor you will have to test it to see if it is in its frequency range. When you're done erase the codes to the computer and see if the problem disappears. 



Question : Do the engine's rpm go high (surge) after start up and then drop quickly that will make it stall ? 


post back your findings.


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## tom99S104x4 (Aug 10, 2009)

hi, i just had the code po101 on my 99 S10 4.3 v6. and i purchased a can of CRC mass air flow sensor cleaner from my local auto parts store and it worked great. you just spray the little wires across the poles and spray the screen ,then let it dry for a 1/2 hour or so and then reinstall it. i put mine back in started the truck and the code was gone. hope this helps.


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## GZ (Jan 31, 2010)

I talked with the owner and told him to sign up for an account and come to this thread, but apparently he did not do that as of yet. 

I am not entirely convinced it is a sensor issue, because in my experience, Cam Position Sensors and MAF or MAP readings being out are indicative of a timing problem. Unfortunately, I do not have access to his truck to run any tests.


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