Mobile Engine Diagnostics for Rough Running, Stalling & No-Starts

Running Rough, Stalling, or Won't Start — With or Without a Warning Light

Plenty of drivability problems never set a code: a rough idle that comes and goes, hesitation when you merge onto Loop 1604, stalling at a light once the engine is warm, or a car that cranks fine but won't fire. Those are the jobs a code reader can't solve, because there's nothing stored to read. The cause is usually a vacuum leak, a weak fuel pump, a failing ignition coil, a dirty throttle body, or a sensor that's drifting out of range without failing outright.

That's the difference between a parts-store scan and a professional diagnostic: we test the system while it misbehaves, not just read what the computer remembered. If your check engine light is on, see our mobile check engine light diagnostics page.

What a Mobile Engine Diagnostic Covers

Danny arrives with a bi-directional OBD2 scanner that reads all control modules — not just the engine. He pulls live sensor data: oxygen sensor switching speed, fuel trim percentages, MAF airflow values, and misfire counters. He captures freeze-frame data that shows exactly what your engine was doing when the fault triggered. For intermittent faults that don't always set a code, this freeze-frame data is often the only way to reproduce the condition without hours of test driving.

You receive a written summary of findings with prioritized repair recommendations. No upselling. No "you need to leave the car" delays. Most diagnostics wrap up in 45–90 minutes at your location.

The $95 Diagnostic Fee — Here's How It Works

The diagnostic fee is $95 flat. If you hire Danny to complete the repair at the same visit, the full $95 is credited toward your repair total. You only pay the standalone diagnostic fee if you choose not to proceed with the repair — which is always your decision, with no pressure.

Most shops charge $100–$150 for a diagnostic and don't credit it toward anything. Dealerships often charge $175+ just to pull codes and write up an estimate.

Common Drivability Problems We Diagnose in San Antonio

Crank-no-start (fuel pump, crankshaft position sensor, ignition), rough or surging idle (vacuum leaks, dirty throttle body, idle air control), hesitation under acceleration (weak fuel delivery, clogged injectors, failing coils), stalling when warm (sensor drift, EGR faults), and loss of power on the highway (restricted exhaust, transmission slipping). We also read ABS, SRS airbag, TPMS, and body control modules — most shops only read engine codes.