Stop losing two hours to a fault code.
Guided diagnostics for diesel and HVAC techs. Enter the code and the symptom, get the test sequence — what to check first, what reading confirms it, what to rule out.
Pro members only · unlimited diagnostics
VIN, serial and fault-code lookups unlock the moment your Pro membership is active.
What an answer looks like
A real DPF derate on an ISX15 — narrowed cause list first, then the order to test in. This is a saved example; running your own codes requires Pro.
Code: SPN 3251 FMI 0 — DPF differential pressure above normal 2018 Cummins ISX15 · derate at 55 mph, regen won't complete Most likely causes 1. Soot-loaded DPF that never completed a regen (short-haul duty cycle) 2. Delta-P sensor hoses plugged, kinked, or swapped 3. Failed delta-P sensor reading high with the engine off 4. Doser injector not delivering fuel — no exhaust temp rise during regen Test sequence 1. Engine off, key on: read delta-P. Should be ~0 kPa. Anything over 0.5 kPa means the sensor or hoses are the fault, not the filter. 2. Pull both sensor hoses, check for soot packing and cracks. Blow clear. 3. Compare hose orientation to the OEM routing — inlet to the front port. 4. Command a stationary regen. Watch DOC-out temp: it must climb past 1000°F within 6 minutes or the doser side is the problem. 5. Still high with the filter hot and clean hoses: filter is loaded — pull and bake or replace, then run the ash-accumulator reset. Can it keep running? Yes, at reduced power, but every mile packs the filter tighter. Get the regen done before the second-stage derate drops you to 5 mph.
What you get
- Unlimited fault-code diagnostics
- Guided test sequences with real specs
- VIN and serial-number unit lookup
- Saved job tickets and diagnostic history
- Cancel anytime, no contract
- Pro members only — no per-lookup charges
14-day refund guarantee — cancel anytime from your billing portal.
Already subscribed? to update your card or cancel.
Who it's for
Flat-rate guys who lose the morning chasing a code that turns out to be a chafed harness.
One-truck outfits who need a second opinion on the shoulder, not a two-hour forum search.
Shops training green techs who need the test order right the first time.
What it will not do
- It is a diagnostic aid, not a substitute for OEM service information. Torque specs, wiring pinouts and repair procedures get verified against the manufacturer's data before you turn a wrench.
- It cannot read your ECM. You supply the codes, the symptoms and the live data; it sequences the troubleshooting.
- It can be wrong. On rare codes and one-off wiring problems it will give you a starting point, not a verdict.
- The tech makes the final call. Nothing here overrides your eyes, your gauges, or shop safety procedure.
Questions
- What engines and equipment does it cover?
- Heavy-truck and off-road diesel (Cummins, Detroit, Paccar, CAT, International), light-duty diesel and gas, plus HVAC/R equipment. Fault codes, symptoms, or both.
- Is this just a search engine with a chat box?
- No. It's built around diagnostic sequencing: what to test first, what reading confirms or clears each cause, and what to stop chasing. It answers in the order a tech actually works.
- Does it replace OEM service information?
- It does not. Torque values, wiring pinouts and repair procedures must be confirmed against OEM service data before you turn a wrench.
- How many diagnostics do I get?
- Unlimited once you're a Pro member. There are no credits and no per-lookup charges.
- Can I cancel?
- Yes, any time from the billing portal. Access runs to the end of the period you already paid for.
- Can I use it for my whole shop?
- Yes. Every tech with a Pro account gets unlimited diagnostics on their own login.
- Do you store my truck data?
- Your job tickets, units and diagnostic history are saved to your account so you can pull them back up. Nothing is sold or shared.
Diagnose faster, bill more.
One saved hour a month pays for the year. Unlimited diagnostics with Pro.