Need help with engine codes! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

WELD4DAYS · 07-15-2008, 06:30 PM

I have a 2002 Silverado with 4.3 V6,5 speed.My engine light has been on for awhile.It is using alot of gas and it's missing when you drive it.The first code is P0102(mass air flow low input).The secon code is P0420(catalyst bank 1)something like that.I've heard it could be the Mass airflow sensor,or maybe the O2 sensors.Can someone help me on where to start looking for the problem.It has lost power.It has about 80,000 miles on it.I don't want to buy sensors that I don't need.Please give me any advice you might have.Thanks alot.

**bwood** · 07-16-2008, 11:39 PM

I have delt with similar issues on S10 Blazers with the same engine. The most recent got worse over a period of about a year. It finally got to the point that it would stall if the AC was on when it started. The mileage dropped to about 10 from 18ish. THe MAF sensor lit the SES light. I replaced it with a new NAPA unit and now it runs like a new one. They make a MAF sensor cleaner (I believe CRC chemicals makes it). It is suppost to safely clean the sensor and remove residue. I have seen excess oil from over oiled K&N filters collect on the MAF screen and sensor wires. This spray worked well to remove the oil.

WELD4DAYS · 07-17-2008, 10:08 AM

Thanks for your help. I guess I will pick up a MAF. I really hope thats the problem.It's not a cheap part.I have a K&N filter right now and I tried cleaning the MAF.I probably used carb cleaner. I don't know if that would hurt it.I'm going back to a stock filter when I get the new sensor.I hope to pick one up today.Thanks

07-15-2008, 06:30 PM	#1
WELD4DAYS Registered User Join Date: Nov 2007 Location: Phoenix,AZ Posts: 107	Need help with engine codes! I have a 2002 Silverado with 4.3 V6,5 speed.My engine light has been on for awhile.It is using alot of gas and it's missing when you drive it.The first code is P0102(mass air flow low input).The secon code is P0420(catalyst bank 1)something like that.I've heard it could be the Mass airflow sensor,or maybe the O2 sensors.Can someone help me on where to start looking for the problem.It has lost power.It has about 80,000 miles on it.I don't want to buy sensors that I don't need.Please give me any advice you might have.Thanks alot.

07-16-2008, 11:39 PM	#2
bwood Registered User Join Date: Jan 2003 Location: Denison, Texas Posts: 1,919	Re: Need help with engine codes! I have delt with similar issues on S10 Blazers with the same engine. The most recent got worse over a period of about a year. It finally got to the point that it would stall if the AC was on when it started. The mileage dropped to about 10 from 18ish. THe MAF sensor lit the SES light. I replaced it with a new NAPA unit and now it runs like a new one. They make a MAF sensor cleaner (I believe CRC chemicals makes it). It is suppost to safely clean the sensor and remove residue. I have seen excess oil from over oiled K&N filters collect on the MAF screen and sensor wires. This spray worked well to remove the oil. __________________ 1998 GMC Sierra SLE 1/2 ton 2WD 305 Vortec -Gibson Stainless Cat Back Swept Side -SS Wheels 2005 Honda CRF250R 2006 Honda CRF150F

07-17-2008, 10:08 AM	#3
WELD4DAYS Registered User Join Date: Nov 2007 Location: Phoenix,AZ Posts: 107	Re: Need help with engine codes! Thanks for your help. I guess I will pick up a MAF. I really hope thats the problem.It's not a cheap part.I have a K&N filter right now and I tried cleaning the MAF.I probably used carb cleaner. I don't know if that would hurt it.I'm going back to a stock filter when I get the new sensor.I hope to pick one up today.Thanks



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