P0300 code with cel on

[searay220]

Check engine light has been on for a couple of weeks. I thought it was from the gas cap again but it isn't. Pulled codes and got a p0300. Reading about this code it could be a bunch of things causing this. The truck runs and drive just fine. I cleared the codes yesterday and ran the truck for about 30 minutes without the light coming back on. Today the light came back on the second I started it. Possibly a crank sensor?? What do think any help would be great.

Thanks

[mike94silverado]

what year and engine?

[searay220]

It's a 2006 GMC Sierra 2500hd 6.0L.

[Chris]

Could be crank sensor could be anything. Start by plugs and wires. How old are they?

[scooby5121]

Fuel pressure test. Then throw parts at it. Tune up !

[searay220]

Recent tune up within the last 6k miles. Wires and plugs.

[txab]

Fuel pressure test. Then throw parts at it. Tune up !

+1 on pressure test. Check intake gaskets as well

[jsklenar]

Best bet is to use a scan tool and see what cylinders have the misfires.

[searay220]

Over the weekend I replaced the crank sensor now I have more codes. I have the P0300,P0056,P0056 pend,P0060. The 56 and 60 codes are O2 sensor codes. The check engine light is still on after I cleared it and when I am on the highway the CEL flashes and goes solid when I get off the highway. Does this make any since to anyone. Is this the result of not doing a crank relearn perhaps?

[mikejr247]

Last time i saw a truck in the shop with this problem the catalytic converters were starting to clog.. how many miles are on the truck and do you have o2 sensor readings?

[searay220]

The truck has 85k miles on it and I will have to see if my cheapo scanner will display the o2 readings.

[searay220]

After replacing the crank position sensor I had a shop do the crank relearn. Light came on as soon as I got on the highway. The check engine light flashes when traveling highway speed and under a load and then stays solid at slower speeds and around town driving. The shop said for me to come back and they will do it again maybe it didn't take they said.

 

The truck has no running issues and all seems fine.

 

Any idea's??

 

 

Also can anyone recommend a scan tool to purchase that does the relearn and other things? Keeping cost an issue.

[searay220]

Could not doing a crank relearn or doing it wrong result in the misfire p0300 staying and creating a p0056 o2 sensor code?

I did replace the the crank position sensor and the o2 sensor with no success.

[txab]

Get a crank re-learn done first. Also check the O2 wiring and fuses

[searay220]

I got the relearn done from a shop but didn't feel confident in there ability. So I'm not sure they did it correctly.

This has whats been done so far:

plugs inspected

wires inspected both new within a year

tested fuel pressre

check for intake leaks

tested fuel injectors

clean MAF

clean intake

replaced o2 sensor

inspected wiring

replaced o2 fuses

 

Not sure what else to do except have another shop do the relearn again..... maybe the first shop did it wrong or it didnt take.

Thanks