2004 Ford F150 5.4L Engine P0011 and P0021 Fault Codes at 180k Miles
My 2004 Ford F15-0 with 180,000 miles is showing P0011 and P0021 diagnostic trouble codes. I recently performed an oil change using Pennzoil Ultra 5W-20 synthetic oil with a Wix filter. I also replaced both Variable Cam Timing (VCT) actuators from Duralast (known to be low quality) with genuine Ford OEM units. After the replacement, the P0021 code disappeared. However, when I added one quart of Rislone engine detergent to the oil, the P0021 code returned. The truck runs poorly only during acceleration at 55 mph. Is it safe to continue driving while the detergent is breaking down sludge? Does this affect engine performance or long-term reliability?
As long as there are no misfire codes, the vehicle should be drivable. Focus on monitoring for any loss of power or rough idling.