P0300 Code - The 1947 - Present Chevrolet & GMC Truck Message Board Network

rickrod3 · 11-13-2018, 11:10 PM

My truck an 05 Silverado with a 6.0 Engine seems to run good.
My check engine light comes on giving me a P0300.

The following is the freeze frame data:
DTCFRZF P0300
Fuel sys 1 CL
Fuel sys 2 CL
Load % 43.5
ECT F 377
SHRTFT1% -0.8
Longft1% 6.3
SHRTFT2% -0.8
LongFT2%4.7
Map KPA 50.0
RPM 2488
VSS 65 MPH
Spark advance 33.5
IAT 48 out door was 40
MAF g/s 54.23
TP% 29.4

The ECT of 377 jumped out at me so I went out to the truck to see what the temperature guage read it was around 210 I connected the scanner to live data and the ECT read 201 F but the IAT read 91F when it was 40F

I guess I'll be checking out these 2 sensors
Any advice would be appreciated

Rick

EVRLET · 11-14-2018, 02:48 AM

Most people don’t believe that a bad coolant sensor can cause a misfire. However, the computer that sees a “really hot temp” will compensate for what it thinks is a lean condition. I would bet that you have a faulty ECT sensor. Let us know if that’s the case.

rickrod3 · 11-14-2018, 10:17 PM

Thanks for your reply Evrlet

I cleared the code, drove home as I did yesterday with the scan tool on live data and I attempted to make the code come back by driving and a hard acceleration like last night the SES light flashed but did not stay on so no code.

I did start fooling with the connector but it got too late for work and I had no time.

I was monitoring the ECT and it got no higher than 202 degrees F

**hatzie** · 11-15-2018, 03:20 PM

Is there a problem with the connector, corrosion, or damage to the wiring to the ECT sensor?

Try Deoxit D5 on the connector and sensor pins then plug/unplug it several times???

rickrod3 · 11-16-2018, 06:02 PM

Thanks I'll try that

**hatzie** · 11-16-2018, 08:05 PM

It's not impossible to have the sensor flaking out intermittently too... I usually don't shotgun stuff but... They're cheap.

OutlawDrifter · 12-30-2018, 08:40 PM

I had a P0300 I chased on my LQ9 swapped Z28 for a year. Finally found it with a noid light set. Ended up being a fuel injector plug that had 1 strand of copper left connecting it.

I agree a faulty sensor could be the culprit. Grounds are a huge player in the LS engines as well, make sure they are all clean. Next place I would look into was plugs/wires.

11-13-2018, 11:10 PM	#1
rickrod3 Registered User Join Date: Aug 2012 Location: Oakland NJ Posts: 27	P0300 Code My truck an 05 Silverado with a 6.0 Engine seems to run good. My check engine light comes on giving me a P0300. The following is the freeze frame data: DTCFRZF P0300 Fuel sys 1 CL Fuel sys 2 CL Load % 43.5 ECT F 377 SHRTFT1% -0.8 Longft1% 6.3 SHRTFT2% -0.8 LongFT2%4.7 Map KPA 50.0 RPM 2488 VSS 65 MPH Spark advance 33.5 IAT 48 out door was 40 MAF g/s 54.23 TP% 29.4 The ECT of 377 jumped out at me so I went out to the truck to see what the temperature guage read it was around 210 I connected the scanner to live data and the ECT read 201 F but the IAT read 91F when it was 40F I guess I'll be checking out these 2 sensors Any advice would be appreciated Rick __________________ 05 Silverado 2500HD. 6.0 engine

11-14-2018, 02:48 AM	#2
EVRLET Registered User Join Date: Aug 2015 Location: Las Vegas NV Posts: 371	Re: P0300 Code Most people don’t believe that a bad coolant sensor can cause a misfire. However, the computer that sees a “really hot temp” will compensate for what it thinks is a lean condition. I would bet that you have a faulty ECT sensor. Let us know if that’s the case. __________________ Customization is what you want it to look like -- not what other people think it should look like

11-14-2018, 10:17 PM	#3
rickrod3 Registered User Join Date: Aug 2012 Location: Oakland NJ Posts: 27	Re: P0300 Code Thanks for your reply Evrlet I cleared the code, drove home as I did yesterday with the scan tool on live data and I attempted to make the code come back by driving and a hard acceleration like last night the SES light flashed but did not stay on so no code. I did start fooling with the connector but it got too late for work and I had no time. I was monitoring the ECT and it got no higher than 202 degrees F __________________ 05 Silverado 2500HD. 6.0 engine

11-15-2018, 03:20 PM	#4
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: P0300 Code Is there a problem with the connector, corrosion, or damage to the wiring to the ECT sensor? Try Deoxit D5 on the connector and sensor pins then plug/unplug it several times??? __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

11-16-2018, 06:02 PM	#5
rickrod3 Registered User Join Date: Aug 2012 Location: Oakland NJ Posts: 27	Re: P0300 Code Thanks I'll try that __________________ 05 Silverado 2500HD. 6.0 engine

11-16-2018, 08:05 PM	#6
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: P0300 Code It's not impossible to have the sensor flaking out intermittently too... I usually don't shotgun stuff but... They're cheap. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

12-30-2018, 08:40 PM	#7
OutlawDrifter Registered User Join Date: Aug 2012 Location: Northeast KS Posts: 1,788	Re: P0300 Code I had a P0300 I chased on my LQ9 swapped Z28 for a year. Finally found it with a noid light set. Ended up being a fuel injector plug that had 1 strand of copper left connecting it. I agree a faulty sensor could be the culprit. Grounds are a huge player in the LS engines as well, make sure they are all clean. Next place I would look into was plugs/wires. __________________ 1999 GMC Suburban K2500 SLT, 454/4L80E 1991 Z/28, 6.0L/T56 1949 GMC 250, S10 Frame, 6.0L/4L80E Instagram @aceshighspeedshop



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