Q.
In January 2021 I found and purchased a brand new 2019 Ford Mustang GT Premium Convertible. The car was built in June 2019, so sat around for 18 months. I love the car and the sound of the 5.0 Coyote V8 engine. It’s only driven on weekend highway rides with my kids. A week after I brought it home, the check engine light came on, and the FordPass app alerted me,  stating the engine control system is unable to control the fuel pressure as expected. Two trips to the dealer found codes P008A low fuel pressure and P068A related to low battery. The battery was tested, failed, and replaced. A few weeks later, the car stalled with the same messages, but before I could get to the dealer, the check engine light went out and all seemed well. A few weeks after that, the check engine light came on again, with the same messages. Do I have a lemon? Is there some electric gremlin at play? Should I try a trickle charger on the battery since the car is only used on weekends? Any advice will be appreciated as it’s terribly inconvenient to keep running to the dealer. Also, the problems are really ruining enjoyment of the car. 

Starting with a fully charged battery makes sense. In fact, it is possible the replacement battery was not fully charged when it was installed. I would get a float style battery charger (Battery Tender is one brand) and fully charge the battery. I would also use the battery charger whenever the car sits for more than a few days to keep the battery fully charged. Prior to recharging the battery disconnect the cables and touch them together for about a minute. This will completely clear the computer memory. When the car is restarted for the first time it may stall or act odd, until it relearns proper operation. If you still have a problem after this then you will need to go back to the dealer for warranty repairs. 

Q.

My 2019 Kia Soul with 31,284 miles on it has a portion of the warranty that is about to expire. The dealer is offering an extended warranty/service agreement, do you think it might be worth it?

The basic warranty is five years or 60,000 miles whichever comes first. The powertrain warranty is 10 years or 100,000 miles. To me it seems too early to pay for something that will most likely be covered by the factory warranty. 

My car has been safely tucked in my garage due to illness. The battery needs charging to get started. I also plan on getting an oil change, tire check and fluids checked. My car is a 2006 Toyota Camry with only 82,000 miles. My car should be okay, right? 

Let your repair shop know the car has been sitting for a time. In fact, depending how long the car has been sitting it may be best to get it towed to your repair shop. Slow charge the battery and change the oil and check the vital fluids. Check the brakes, tires and add gas stabilizer and gas line antifreeze to the fuel. This will help if the gasoline picked up any moisture. Take it easy with the car until it shakes the cobwebs out. 

I have a fully optioned 2011 Dodge Citadel with the 5.7-liter engine. Over the 10 years I have owned the vehicle it has stalled unexpectedly three times. It appears to be an electrical system failure and the headlights and taillights flicker. The first time it happened, I had the car towed to a dealer and they said they could not find any issues. The last two times it happened I was able to remove the negative cable to the battery. When reconnected, the car started and ran normally. I researched online and I saw some discussion about alternator or computer module problems. What are your thoughts and suggestions on how to diagnose and correct? This is my wife’s car with only 70,000 miles on it and I want her to be able to drive it with confidence.

The first place I would be looking is a faulty ground circuit and poor connections to common relays. Also this vehicle, like many Dodge Durango models, had a recall to the fuel pump relay. Unfortunately, there is also a problem with the replacement fuel pump relay which could lead to stalling. 

Reader comment: 

I ran across your column and appreciate your solid practical advice. I’m a former GM Goodwrench mechanic from the 1980s and have had a couple of other careers since then, but worked my way through college and grad school, working on everything from a 1925 Model A used in a Norman Rockwell painting to Mercedes and BMW. A recent column contained an inquiry on disposal of old diesel fuel.  For diesel and kerosene, some folks (mostly shops but a few rural homes) have heaters that run on used motor oil or diesel.  I ran across a guy on Craigslist who takes my “old” diesel and kerosene and heats his repair shop with it. 

Thanks for the tip, it sounds like you had an interesting career.

--The Car Doctor