Auto Parts FAQ: Hella LED Headlights, Tail Lights & 2016 Catalytic Converters

I'm an auto parts specialist, and I've been handling procurement orders for six years—long enough to personally make seven significant mistakes totaling roughly $2,400 in wasted budget. This FAQ covers the questions I get asked most: what does a crankshaft do, what is the strut of a car, are Hella LED headlights worth it, and what to know before buying a 2016 catalytic converter.

What does a crankshaft do?

The crankshaft converts the up-and-down motion of the pistons into rotational motion that turns your wheels. Each piston connects to the crank via a connecting rod; when combustion pushes the piston down, the rod forces the crank journal to spin. That rotation travels through the flywheel, into the transmission, and down to the drive wheels.

What you really need to know is what a failing one sounds like. In my first year handling parts (2018), a customer came in with a rhythmic knock under acceleration. I recommended spark plugs and a tune-up because the mileage pointed that direction. Two weeks later the knock was worse—scored crankshaft bearings. $2,800 rebuild, most of it labor, and a customer who didn't come back. Now I check oil pressure and run a bearing clearance test before recommending anything else.

The crankshaft position sensor is also worth knowing about. When it fails, the engine won't start or stalls randomly. It's a relatively cheap part, but we've had it misdiagnosed as a fuel pump issue in our own shop—including by me.

What is the strut of a car?

A strut is a suspension component that combines a shock absorber and a coil spring into one load-bearing unit. Unlike a shock, a strut supports the vehicle's weight and often serves as the steering pivot point on front suspensions.

Most drivers judge strut condition by ride comfort—whether they feel every bump. What they don't see is the braking effect. Worn struts let the tire lose contact with the road over bumps, which genuinely increases stopping distance, especially on wet roads.

If you're replacing struts, replace the mounts at the same time. I've had customers decline the mounts to save $90, then come back three months later complaining about a clunking noise. The second labor charge was $240. They paid more overall and had to deal with a car that sounded broken in the meantime.

Are Hella LED headlights worth the upgrade?

Depends on where you drive. Hella's LED headlight assemblies use a projector-style lens with a sharp cutoff—strong light where you need it, without scattering it into oncoming traffic. That's the engineering difference between a complete Hella lamp assembly and a cheap LED bulb swap.

If you regularly drive dark rural or highway roads, I recommend Hella LED headlights. The visibility difference is real. But if you're mostly driving in well-lit city streets, a quality halogen setup is adequate, and spending hundreds on headlights you won't fully use doesn't make sense—at least not for practical purposes.

From the outside, a $40 LED bulb kit looks like the same deal. The reality: most don't produce a proper beam pattern. We've had customers come back asking why their cheap upgrade made visibility worse, not better. Honestly, I'm not sure why the lumen numbers on the box don't translate to real-world performance. My best guess is the optics aren't matched to the light source.

What should I check before buying Hella tail lights?

Two things: DOT compliance and the connector type.

Hella sells DOT-compliant tail lights for street use, but they also make off-road-only versions. In photos, they look nearly identical. I once ordered a set for a customer's trailer without checking the connector—it didn't match the factory harness. $350 in lights, a $120 pigtail adapter, and two weeks of waiting. That one's on my mistake list.

Also ask whether your vehicle needs a load resistor to prevent hyperflash. Hella LED tail lights draw less current than incandescent bulbs, and the flasher can interpret that as a burned-out bulb. It's a $15 fix, but better to know upfront than after installation.

2016 catalytic converter: what should I know?

Two things: theft risk and emissions compliance.

The 2016 catalytic converter contains platinum, palladium, and rhodium—valuable enough to make it a major theft target. If your exhaust suddenly gets loud, the converter was likely cut out in minutes. Shops in our area now weld the converter to the frame and etch VINs to deter thieves.

For replacement, check your state's emissions rules before buying anything. California and several other states require CARB-compliant converters, and CARB publishes an approved parts list. About universal converters: in 2023, I recommended one for a customer's 2016 model to save money, and the mounting angles didn't align with the factory pipes. Double the labor plus adapter sections. I know universal units work fine on some vehicles—just not in my experience with this particular model. For a 2016 with modern emissions systems, I'd go direct-fit—or rather, that's what I'd do now, after learning the hard way.

What's the #1 mistake people make when ordering auto parts?

Assuming the part fits because the listing says it fits.

We've caught 47 potential errors in the past 18 months using a simple pre-order checklist: confirm the OEM part number, verify against the VIN, check the connector or mounting configuration, and note any revision suffixes. It's saved us roughly $8,600 in return fees, restocking charges, and wasted labor.

That checklist exists because of my own mistakes—the ones this article is about. Before you order anything, ask your supplier to confirm fitment against your VIN. If they say "it should fit," treat that as a yellow flag. It either fits or it doesn't.