Call Flow Guide

Is the light solid or flashing?

FLASHING:

STOP DRIVING. Flashing = active misfire. Can damage catalytic converter. Tell them to pull over safely if currently driving.

SOLID: Less urgent, but still needs attention.

Do they have the code? (P0XXX)

YES: Look up code in Mitchell → Diagnostic Trouble Codes

NO: Ask if they can get it read at AutoZone/O'Reilly (free) or describe symptoms

Most Common Codes:

P0420/P0430 - Catalyst efficiency below threshold → Usually O2 sensor or cat converter
P0300-P0308 - Misfire → Spark plugs, coils, injectors, vacuum leak
P0171/P0174 - System too lean → Vacuum leak, MAF sensor, fuel pump
P0440-P0449 - EVAP system → Gas cap, purge valve, vent valve
P0128 - Coolant temp below thermostat range → Thermostat stuck open

Mitchell ProDemand: Search code → Check "Probable Causes" and "Diagnostic Steps" → Look for TSBs related to this code for this vehicle

What happens when they turn the key/push button?

NOTHING (no sound, no lights):

Dead battery or connection issue
Ask: Are interior lights working? If no → Battery dead or terminal corroded
Fix: Jump start, check battery terminals for corrosion, test battery

CLICKING (rapid or single click):

Weak battery or starter issue
Rapid click = Battery has some charge but not enough
Single loud click = Likely starter solenoid or starter motor
Ask: Have them try jumping it. If starts with jump → battery. If still clicks → starter.

CRANKS BUT WON'T FIRE:

Fuel, spark, or air issue
Ask: Does it smell like gas? (flooding)
Ask: When was last tune-up? (spark plugs/coils)
Ask: Any recent fuel fill-up? (bad gas)
Check: Fuel pump - can they hear humming when key is turned to ON?

CRANKS SLOW THEN NOTHING:

Battery dying during crank attempt
Battery too weak to sustain cranking. Needs charge or replacement.

Mitchell ProDemand: Go to "Starting System" → "Symptom-Based Diagnosis" → Select symptom for guided troubleshooting

Where is the noise coming from?

FRONT END:

Squealing on startup → Serpentine belt slipping (worn or tensioner)
Squealing when turning → Power steering low/pump failing (or belt)
Grinding when braking → Brake pads worn to metal
Clicking when turning → CV axle joint worn
Clunking over bumps → Sway bar links, ball joints, or struts
Humming/droning at speed → Wheel bearing

ENGINE:

Ticking/tapping → Low oil, lifter tick, exhaust leak
Knocking → Rod knock (serious), carbon buildup, bad gas
Whining → Alternator, power steering, or AC compressor bearing
Rattling on cold start → Timing chain tensioner (common on many vehicles)

REAR/UNDERNEATH:

Clunking when accelerating/decelerating → U-joints, differential
Dragging/scraping → Loose heat shield, exhaust hanging low
Humming from rear → Rear wheel bearing or differential

Key diagnostic questions:

Does it happen at idle, while driving, or both?
Does speed affect it? (faster = louder?)
Does it change when turning left vs right?
Does it happen when cold, warm, or always?
Does pressing the brake change it?

Mitchell ProDemand: "Noise, Vibration, Harshness" section → Filter by location and type of noise

If currently overheating: Tell them to pull over, turn off AC, turn ON heater full blast, let idle. If temp keeps rising, shut off engine.

Is there visible coolant leak?

YES - Find the source:

Under radiator → Radiator leak or lower hose
Near engine front → Water pump
Sweet smell inside car → Heater core
Under coolant reservoir → Cracked reservoir or cap

NO visible leak:

Check coolant level (when cool) - if low, there IS a leak somewhere
Fans not running → Fan relay, fan motor, temp sensor
Thermostat stuck closed → Won't let coolant flow
Head gasket → White smoke from exhaust, milky oil, bubbles in coolant

When does it overheat?

Only at idle/slow speeds → Cooling fans not working
Only at highway speeds → Airflow blockage, radiator clogged
All the time → Thermostat, water pump, or head gasket

Mitchell ProDemand: "Cooling System" → "Overheating" → Check for common failures on this specific vehicle

What's the symptom?

GRINDING:

Pads worn to metal. Stop driving as soon as possible. Damaging rotors and compromising safety.

SQUEALING (high-pitched):

Usually wear indicator tab touching rotor = pads getting low. Not emergency but service soon.

PULSATING/VIBRATION:

Warped rotors. Caused by heat (heavy braking, stuck caliper). Need rotor resurface or replacement.

SOFT/SPONGY PEDAL:

Air in brake lines, low brake fluid, or master cylinder failing. Check fluid level first - if low, there's a leak.

PEDAL GOES TO FLOOR:

Dangerous. Master cylinder failure, major leak, or brake booster issue. Do not drive.

PULLING TO ONE SIDE:

Stuck caliper, collapsed brake hose, or uneven pad wear. One side braking harder than other.

ABS LIGHT ON:

ABS system fault - regular brakes usually still work. Common causes: wheel speed sensor, ABS module, wiring.

Mitchell ProDemand: "Brake System" → Check for TSBs - many vehicles have known brake issues with specific fixes

Automatic or Manual?

AUTOMATIC:

Slipping (RPMs rise but car doesn't accelerate) → Low fluid, worn clutches, failing torque converter
Hard/harsh shifts → Low fluid, dirty fluid, solenoid issue, or adaptive learning reset needed
Delayed engagement (D or R) → Low fluid, internal wear, or valve body issue
Won't shift out of 1st/2nd → Limp mode - check for codes, could be sensor or solenoid
Shudder/vibration at low speeds → Torque converter clutch issue (common on many vehicles)

First check: Transmission fluid level and condition. Should be red/pink, not brown/black. Should not smell burnt.

MANUAL:

Hard to get into gear → Clutch not fully disengaging, synchros worn, low fluid
Grinding into gear → Synchros worn, clutch issue
Pops out of gear → Worn synchros, shifter linkage, or internal wear
Clutch slipping → Clutch disc worn, needs replacement

Mitchell ProDemand: "Transmission" → Check "Common Problems" - many transmissions have known issues with specific fixes or TSBs

What's not working?

BATTERY KEEPS DYING:

How old is battery? (3-5 years typical life)
Parasitic drain - something staying on when car is off
Alternator not charging - test with multimeter (should be 13.5-14.5V running)
Short trips only - battery never fully charges

LIGHTS DIMMING/FLICKERING:

Alternator failing or loose connection. Check belt tension and battery terminals first.

POWER WINDOWS/LOCKS NOT WORKING:

One window → Window motor or regulator
All windows → Fuse, window switch panel, or body control module
Only from one door → Switch or wiring in that door

RANDOM WARNING LIGHTS:

Often low battery voltage causing computer glitches. Check battery and alternator first before chasing individual warnings.

NO CRANK, NO START, SOME LIGHTS:

Check for anti-theft light flashing - could be key/immobilizer issue. Also check neutral safety switch (try starting in neutral).

Mitchell ProDemand: "Electrical" → Use wiring diagrams to trace circuits. Check fuse locations and relay positions.

Opening Script

Check Engine Light $25

Most Common Codes:

Car Won't Start $35

Strange Noise $30

FRONT END:

ENGINE:

REAR/UNDERNEATH:

Overheating $35

Brake Issues $30

Transmission Issues $40

AUTOMATIC:

MANUAL:

Electrical Issues $35

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