Multi-Point Vehicle Inspection

A multi-point inspection (MPI) is the check a shop performs on a customer's car or light truck during a service visit. It finds unsafe conditions and upcoming maintenance before they leave a driver stranded. No law requires it, but shops rely on it to protect customers and plan repairs, and it is often one of the first jobs a new technician owns.

This is a shop inspection done by a technician in a bay. It is not the pre-trip inspection a commercial driver does before a shift. That is a different job, on a different class of vehicle, under federal trucking rules. It is also not a state safety inspection, which has legal pass or fail rules of its own.

What You Will Be Able to Do

• Work through an inspection in the same order every time.
• Check fluids, belts, battery, lights, tires, brakes, steering and exhaust.
• Rate each item green, yellow or red with a measurement behind it.
• Explain findings clearly and honestly.

How the Rating System Works

Most shops use a three-color form, on paper or on a tablet.

Write down numbers, not opinions. "Front pads 3 mm" is useful. "Brakes getting low" is not. Keep safety items separate from routine maintenance items, so that the customer can tell what cannot wait.

Start in the Driver's Seat

Before the car goes up, sit in it and check these items.

• Warning lights with the key on, and after the engine starts.
• Seat belts: latch and release each one, and look for fraying.
• Horn, wipers on all speeds, and washer spray.
• Parking brake: it should hold without using all its travel.
• Brake pedal: it should feel high and firm. A spongy or soft pedal suggests air in the lines or a failing master cylinder.
• Steering: check for excess play or roughness.
• Mirrors: all present, secure and uncracked.
• Windshield: check for cracks and chips, especially in the area the wipers sweep.

Lights and Exterior

Have a helper work the controls, or use a wall or a mirror for reflections. Check every light: low and high beams, turn signals, brake lights including the center high-mount, taillights, reverse lights, license plate light, fog lights if fitted, and hazard flashers. Look for cracked or fogged lenses and for headlights aimed too high or too low.

Check wiper blades for cracks and tears and for good contact with the glass. Blades that streak or chatter need replacing, and most last about 6 to 12 months.

Under the Hood

Let the engine cool before you touch the cooling system. Keep clear of fans, which can start on their own, and of hot exhaust parts.

Engine oil. Check the level on level ground. Note the color and smell. Fresh oil is amber, and normal used oil is dark brown. Black, gritty oil is overdue for a change, and a burned smell points to overheating or oil breakdown. Oil that looks milky or frothy suggests coolant has mixed with it, possibly from a failed head gasket or a cracked head. Treat it as a red item.

Coolant. Check the level in the reservoir with the engine cool. Look for a rusty, oily or muddy color. Check hoses for cracks, bulges and soft spots, and check the radiator cap seal, the radiator and the water pump area for leaks.

Brake fluid. Check the level. It should sit between MIN and MAX. A low level usually means worn pads or a leak, so make sure the brake inspection confirms which. Dark brown fluid is old and has taken on moisture, which lowers its boiling point. Most makers recommend replacing brake fluid about every 2 to 3 years.

Transmission fluid. Check it if the vehicle has a dipstick, following the procedure in the service information, which is usually at operating temperature. Fresh fluid is often red and clear. Brown fluid or a burnt smell points to overheating or worn clutches.

Power steering fluid. Check the level on hydraulic systems, and listen for a pump whine.

Drive belt. Look for cracks, fraying, glazing and missing chunks. Modern belts can wear with few cracks, so use a rib wear gauge if your shop has one. Check that the automatic tensioner is within its wear marks.

Battery. Check for clean terminals, a tight hold-down and a sound case. Test it with a conductance tester, and compare the result with the battery's rating. A healthy battery usually reads 80 percent or more of its rated cold cranking amps. Note its age, because many batteries last only about 3 to 5 years, and less in hot climates.

Air filter. Remove it and hold it up to a light. If light does not pass through, it is due. Check the filter box for debris and rodent nests. Replace it according to condition and the maker's schedule.

Washer fluid. Top it up.

Warning: Never open a radiator cap on a hot engine. On hybrids and EVs, do not touch orange cables or any high-voltage part. Stick to the checks the shop has approved for that vehicle.

Tires and Wheels

• Measure tread depth at the inner, center and outer grooves of each tire, and record the numbers in 32nds of an inch.
• Check and set pressures to the door placard.
• Look for cracks, bulges, cuts and embedded objects.
• Read the wear pattern. Cupping or scalloped wear points to worn shocks or struts, or to balance problems. Note any edge wear for an alignment check.
• Read the DOT date code on each tire. Flag tires older than 6 years, regardless of tread depth.
• Check the spare, the jack and the wheel lock key.

On the Lift

Raise the car on the correct lift points and rest it on the locks.

Brakes

Pull the wheels if your shop's inspection includes it. Many shops do on a full MPI, and at minimum you need a clear view of both pads.

• Measure pad thickness. Compare to your shop's limit, the maker's spec and any state rule. Many shops call 3 to 4 mm a yellow item and 2 mm a red item.
• Look at rotors for scoring, grooves, heat spots and rust. With the wheels off, measure thickness with a micrometer and compare it to the minimum spec.
• Check hoses for cracks, chafing, bubbles and bulges. A bulge means the hose is weak and could burst under pressure.
• Check steel lines for rust, kinks and leaks.
• On drum brakes, check shoe thickness, wheel cylinders and hardware if the drums are off.

Steering and Suspension

• Rock the wheel at 12 and 6 o'clock to check for wheel bearing and ball joint play. A worn bearing may fail and cause a wheel to separate from the vehicle.
• Rock it at 3 and 9 o'clock to check for tie rod play.
• Spin each wheel and listen for roughness or growling, which points to a worn bearing.
• Check boots on ball joints and tie rods.
• Inspect control arm bushings, sway bar links and steering rack boots.
• Look for broken springs.
• Check shocks and struts for a wet, oily film, which means the seal has failed and the unit is leaking.
• With the car on the ground, push down on each corner and let go. If it bounces more than once, the shocks or struts are likely worn.

After a curb or pothole strike, inspect wheels, tires and suspension parts for bends and cracks.

Axles, Driveline and Leaks

• Check CV boots for any tear, crack or split that lets grease out. A split boot ruins the joint if water and dirt get in.
• Check U-joints on rear-wheel-drive vehicles for play.
• Look for wet spots at the differential. A wet seal or gasket can starve the gears of oil.
• Trace any leak to its source and identify the fluid.

Colors vary by product, so confirm by where the leak is. Fluid on the inside of a wheel or tire is an urgent brake concern.

Exhaust

Follow the system from the engine to the tailpipe. Check for rust holes, leaks, loose clamps and broken hangers. A hole or leak is a red item, since exhaust gas can enter the cabin. A leak ahead of an oxygen sensor can also set false lean codes. Tap the catalytic converter gently with a rubber mallet when the system is cool. A rattle may mean its internal substrate has broken.

Body and Frame

Look for heavy rust on the frame, subframe and rocker panels, particularly in salt-belt states. Rust through a structural part is a red item.

Worked Example: Filling Out the Form

A 9-year-old sedan comes in for an oil change. You find:

The battery reads 460 / 600 = 77 percent, so it is under the 80 percent guide. Tires with the date code 2118 were made in the 21st week of 2018, which makes them about eight years old. The cupped tire points to a worn strut, so the advisor should also see that note. Your report lists the safety item first, followed by what can wait.

Reporting Your Findings

• Record the customer's name, vehicle, mileage and date.
• Use measurements and colors for every item you checked.
• Take a photo of each concern, such as a torn boot or a leak.
• Hand the form to the service advisor. In most shops, the advisor talks to the customer.
• Keep the record. It helps with the next visit, and it protects the shop.

An inspection is only useful if people can trust it. Mark what you actually measured. Never pencil in a check you did not do, and never call a good part bad to create a sale. A customer who trusts the report comes back. A false red item can end a career, and in some states it can be treated as fraud.

Common Mistakes

Check Your Understanding

1. On a routine oil change, you see a brake hose with a bubble on it. How do you rate it? Red. It could burst, so tell the advisor right away.
2. The oil on the dipstick looks like a milkshake. What do you suspect? Coolant in the oil, possibly from a head gasket failure. Report it as a red item, and do not just change the oil.
3. The reservoir is below MIN, and the pads measure 7 mm. What does this point to? A probable leak, because the pads are not worn enough to explain it. Look at calipers, wheel cylinders, lines and hoses.
4. A truck driver asks if your form counts as the pre-trip for his tractor. What do you say? No. A shop's multi-point inspection does not replace the inspection a commercial driver must complete.

Key Takeaways

• A multi-point inspection is a shop service check on cars and light trucks. It is not a commercial pre-trip or a state inspection.
• Follow the same order every time, and record measurements.
• Green means OK, yellow means soon, and red means safety or repair now.
• Low brake fluid means worn pads or a leak. Find out which.
• Bulged hoses, milky oil, exhaust holes and loose steering parts need immediate attention.
• Report honestly. The value of the inspection depends on it.