low oil pressure cause P0300?
low oil pressure cause P0300? Working on a 2011 Cadillac Escalade ESV AWD. 200,000 miles. The vehicle was only purchased for the 6.2/6L80 drivetrain for eventual transplant in to a square body Suburban. It is roadworthy and plan to correct the issues and semi-daily it.
Upon purchase, the codes were P0300 random misfire and multiple Sensor 2 heater circuit codes for both banks. Driving the truck the 40 miles home, it ran great from stop sign to stop sign. But when stopped at idle , you'd feel the engine start missing and shaking and multiple lights would appear on the dash. Not just CEL, but suspension system also. Once back on the throttle, all is good.
We put on new plugs and wires. Replaced both downstream 02 sensors with no change to anything I described above. Next going to test for heater circuit voltage at the sensors and see where that leads us.
My first question is, can low oil pressure cause anything we're seeing here? Monitoring on the dash, the OP is as low as 8 at idle when the engine starts missing. I only have Torque Pro to help diagnose and I can see the fuel pressure rise to 58 and the ECM change to Open Loop when this happens. And it does happen every time at idle.
When running good, the fuel pressure drops to 43 when in closed loop idling correctly, but won't stay there for long before changing to Open Loop and FP rising.
Any ideas?
Upon purchase, the codes were P0300 random misfire and multiple Sensor 2 heater circuit codes for both banks. Driving the truck the 40 miles home, it ran great from stop sign to stop sign. But when stopped at idle , you'd feel the engine start missing and shaking and multiple lights would appear on the dash. Not just CEL, but suspension system also. Once back on the throttle, all is good.
We put on new plugs and wires. Replaced both downstream 02 sensors with no change to anything I described above. Next going to test for heater circuit voltage at the sensors and see where that leads us.
My first question is, can low oil pressure cause anything we're seeing here? Monitoring on the dash, the OP is as low as 8 at idle when the engine starts missing. I only have Torque Pro to help diagnose and I can see the fuel pressure rise to 58 and the ECM change to Open Loop when this happens. And it does happen every time at idle.
When running good, the fuel pressure drops to 43 when in closed loop idling correctly, but won't stay there for long before changing to Open Loop and FP rising.
Any ideas?
The idle rpm might be low because of the misfire and the lower the rpms the lower the oil pressure will fall. With 200,000 miles you could have one or more injectors dirty and dribbling fuel at idle. With that many miles it might be worth sending them in to be checked/cleaned.
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Pull oil pressure sensor and replace cause it's cheap and while sensor is out pull strainer under it and see if it's plugged if it's fine throw it over your shoulder and install the new sensor. Fire it up and see where it's at. Get GM only sensor don't waste your money on parts house garbage. The oil pressure sensor reading is reliable without having to put a pressure gauge on it if you don't have one. Oil comes from the pump through the filter directly up the rear of the block oil gallery to the oil pressure sensor and heads to the lifters from there.
Low oil pressure can cause misfire due to insufficient and or aerated oil supply to the lifters.
The various suspension and traction control warnings etc are normal they are disabled by the pcm under varying conditions when they are out of normal spec.
If it's still low but there are no rattles ticks or knocks afterwards time for an oil pump and oring.
Low oil pressure can cause misfire due to insufficient and or aerated oil supply to the lifters.
The various suspension and traction control warnings etc are normal they are disabled by the pcm under varying conditions when they are out of normal spec.
If it's still low but there are no rattles ticks or knocks afterwards time for an oil pump and oring.
Last edited by 01WS6/tamu; Mar 4, 2025 at 08:34 PM.
The idle rpm might be low because of the misfire and the lower the rpms the lower the oil pressure will fall. With 200,000 miles you could have one or more injectors dirty and dribbling fuel at idle. With that many miles it might be worth sending them in to be checked/cleaned.
Since mid 2003 anything GM that has the newer 3-wire Oil Pressure Sender is programmed with it to start shutting down the Engine if the Oil Pressure gets low. I've worked on several that had the same exact symptoms as above and the fix was a new Oil Pressure Sender, why I mentioned that already in my first post. It's a programmed failsafe.
Since mid 2003 anything GM that has the newer 3-wire Oil Pressure Sender is programmed with it to start shutting down the Engine if the Oil Pressure gets low. I've worked on several that had the same exact symptoms as above and the fix was a new Oil Pressure Sender, why I mentioned that already in my first post. It's a programmed failsafe.[/QUOTE]
Thanks for all the replies.
I was hoping the misfires was a fail safe
We'll be replacing that soon and update the post
Thanks for all the replies.
I was hoping the misfires was a fail safe
We'll be replacing that soon and update the post
Considering how I have a 2001 2500HD with a LQ4 6.0l about to turn 200k miles that idles at almost 60psi with original stuff I disagree with the above.
Since mid 2003 anything GM that has the newer 3-wire Oil Pressure Sender is programmed with it to start shutting down the Engine if the Oil Pressure gets low. I've worked on several that had the same exact symptoms as above and the fix was a new Oil Pressure Sender, why I mentioned that already in my first post. It's a programmed failsafe.
Since mid 2003 anything GM that has the newer 3-wire Oil Pressure Sender is programmed with it to start shutting down the Engine if the Oil Pressure gets low. I've worked on several that had the same exact symptoms as above and the fix was a new Oil Pressure Sender, why I mentioned that already in my first post. It's a programmed failsafe.
They will pcm shuts it down under either 3 or 5 psi seen it many times over the years on cust trucks w failed pumps. Funnier part is the well it's done that for months but I didn't worry about it.