Hi,
We need to focus on the fuel rail code. A pending code is a little different. Pending codes are typically generated when the vehicle's onboard systems detect a potential issue or anomaly but have not yet confirmed it as a persistent problem. They act as early warning signals for potential malfunctions that may develop into permanent trouble codes if the problem persists over a certain number of drive cycles.
The pending code, in this case, has become an active one already.
As far as the code, P0191, it can be caused by a few things. The sensor could be failing, there could be a fuel pressure issue, an engine vacuum leak can cause it or even low fuel.
When the vehicle is running, does it have a smooth idle? You mentioned it sits more than driven. Has it been a long time since it was driven?
Let's do a couple basic checks. First, the sensor is located on the fuel rail. There will be a vacuum hose going to it. Check the line to make sure it is good and not cracked or disconnected. See pic 1
Next, check for engine vacuum leaks.
Here is a link that explains how it's done:
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
Let me know what you find. Also, when you check the vacuum hose at the sensor, make sure there is no evidence of fuel getting into it.
Take care,
Joe
See pic below.
Image (Click to make bigger)
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Sunday, July 9th, 2023 AT 7:39 PM