Diesel in a Gas Engine: What it Costs to Repair

Diesel in a Gas Car: What it Costs

Here’s a firsthand account of someone who had put diesel in a gas engine, what happened, and what the services cost to fix the issue. Word to the wise: don’t zone out while gassing your vehicle; putting diesel in a gas car is an expensive mistake.

One day, I received a call from my husband. He was on the side of the road in our three-year old BMW 1-series, waiting for roadside assistance. Out of nowhere, the car had started sputtering, and eventually it slowed from highway speeds down to a crawl, then it stalled and wouldn’t restart.

Cost of Diesel in Gas Car Openbay

The car was still under warranty, so roadside assistance towed it to the BMW dealership. When the service department had some time to look it over, they called us to ask, “Had the car been gassed shortly before this happened?” and the answer was, “Yes.” Sure enough, it was our fault: the technicians detected diesel when they’d found fouled spark plugs, tested some of the fuel. After a couple of days of my husband swearing up and down that the diesel gas pump must have been mislabeled as regular gasoline, he began to admit that it had been a bit of a struggle to get the oddly shaped nozzle into the fuel tank that day. Turns out that if you’re determined enough, you can get that square peg into a round hole and fill your gas car with diesel.

The dealer recommended we get new catalytic converters, which would amount to more than $4,000 worth of labor and parts. We immediately started asking around, and Googling, “What do catalytic converters do?” and why were they so expensive – were these things coated with diamonds or something? Not too far from it – it turns out that catalytic converters use precious metals, including platinum, to chemically convert toxic gasses into cleaner exhaust before it exits your tailpipe.

Check Out:  100,000 Mile Service - What's the Cost?

putting gas in a diesel vehicle is an expensive mistake

Because the cost of replacing the catalytic converters was so high, we initially declined to have them replaced. Instead, we opted to get the car back on the road, hoping the precious catalytic converters would have survived the trauma unscathed. For the first service, we had the diesel fuel drained out, the gas tank cleaned, six spark plugs replaced, fuel pump replaced, five gallons of new fuel added.

Still not cheap, this service would cost us $1854.23. Throw in the nearly $60 worth of diesel they’d drained out, and we’ve now paid $1,913.03. To add insult to injury, when I left the dealer, I had to pay to fill the car with gas, choosing the fuel nozzle carefully, of course!

Despite the pricey repair, the car wasn’t perfect. When I went to pick up the car at the dealer, the notes indicated we might have issues with the fuel injectors down the line. And, as the service advisor handed me the keys, he said, “It still might give you some issues. … Like the car stalled before I pulled it around here, and you’ll probably have the check-engine light on.” Great.

Dealer repair order for initial cleaning of diesel from gas car

Sure enough, that same day, the check-engine light came on, and it never went off. We just ignored it, figuring it was a small price to pay for an operable vehicle. And we got used to the faint smell of diesel coming from the exhaust.

Check Out:  Why Do I Need an Annual Brake Inspection?

Fast forward six months, when it was time for our annual vehicle inspection, which the car failed. Turns out the emissions were spewing dirty air, and Massachusetts wouldn’t allow its operation. Time to break out the old checkbook for the final fix, and this time, we chose an independent shop.

After an $85 diagnosis, the shop said we probably needed to replace our two catalytic converters. They offered a less expensive alternative first (yes, please!), of installing new oxygen sensors, to see if the issue would go away. That would cost $750, and we accepted. If the new oxygen sensors didn’t pass the emissions test, they promised to install the catalytic converters, minus the labor costs, given both services required lots of labor to remove the exhaust system.

Changing out the oxygen sensors didn’t work, so we wound up having them install two new catalytic converters, which alone (minus the labor) cost $1,798.94. Total spent at the independent shop was $2634. Add that to the initial repairs, and putting diesel in a gas engine wound up costing $4,546.97. Pretty pricey for one tank of gas.

All fixed, we drove the car back to the vehicle inspection station and passed. That was three years ago this month, and it’s since not cost us anything, beyond basic maintenance… until we got the below note on the windshield, from a friendly stranger, and learned the higher price of run-flat tires. But that’s another blog for another time.

Friendly Stranger's Note - Tire Blown