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Littleton, CO

Engine Diagnostics

Check engine light on? Something feels off? AutoTrek's advanced OBD-II diagnostic system reads every fault code and live data stream across your entire vehicle — pinpointing the exact cause fast, so repairs are targeted and accurate.

ASE Certified Technicians
Advanced OBD-II Equipment
Written Digital Report
All Makes & Models

What's Included

Comprehensive Diagnostic Services

A code reader from the parts store tells you a number. AutoTrek tells you what's actually wrong — and what it will take to fix it correctly.

OBD-II Fault Code Scan

Full retrieval of all stored, pending, and permanent Diagnostic Trouble Codes across engine, transmission, ABS, airbag, and body control modules.

Live Data Stream Analysis

We monitor real-time sensor data — oxygen sensors, MAF, coolant temperature, fuel trims, and more — to identify intermittent faults that don't always trigger a code.

Component Testing

Targeted testing of sensors, actuators, solenoids, and modules to confirm which specific component has failed — not just which system is affected.

Written Diagnostic Report

You receive a full written report detailing every code found, what it means, the likely root cause, and our recommended repair with a cost estimate.

Expert Interpretation

Fault codes point to a system, not always the exact part. Our ASE Certified techs apply experience and additional testing to confirm the true root cause before recommending repairs.

Emissions Readiness Check

We verify that all emissions monitors are complete and ready for Colorado's emissions testing program before you make a wasted trip to the station.

Why It Matters

Don't Guess. Know.

A check engine light alone doesn't tell you if you need a $15 gas cap or a $1,500 catalytic converter. Without proper diagnostics, shops guess — and guessing leads to replacing parts that don't fix the problem. AutoTrek uses professional-grade scan tools and live data analysis to get the right answer the first time.

Our diagnostic fee is credited toward any repair work you choose to have done at AutoTrek. You're not paying just for a code — you're paying for an expert diagnosis that leads to a targeted, cost-effective fix.

Schedule Diagnostic

Warning Signs

Signs You Need a Diagnostic

Check engine light is on — solid or flashing, a fault code is stored and needs to be read and interpreted.

Rough idle, misfiring, or engine hesitation — could be a sensor, ignition, fuel delivery, or mechanical issue.

Sudden drop in fuel economy — a failed sensor or fuel system component often causes a measurable MPG loss.

Failed emissions test — we diagnose the failing monitor or code and repair what's needed to pass.

Stalling, hard starting, or no-start condition — diagnostic quickly isolates the faulty system causing the problem.

Common Fault Codes

Codes We See Every Day

These are among the most frequent OBD-II codes AutoTrek diagnoses and repairs for Littleton, CO drivers.

P0420

Catalyst Efficiency Below Threshold

Catalytic converter degraded or failing. Can also be caused by an O2 sensor or exhaust leak upstream.

P0300

Random/Multiple Cylinder Misfire

Engine misfiring on multiple cylinders. Often spark plugs, coils, injectors, or a vacuum leak.

P0171

System Too Lean (Bank 1)

Fuel mixture too lean. Common causes: MAF sensor, vacuum leak, fuel pressure issue, or O2 sensor.

P0442

Evaporative Emission Leak (Small)

Small EVAP system leak. Often just a loose or faulty gas cap — or a cracked EVAP hose or purge valve.

P0128

Coolant Temp Below Thermostat

Engine not reaching operating temperature. Typically a faulty thermostat that's stuck open.

P0507

Idle Control System High RPM

Idle speed too high. Often a dirty throttle body, vacuum leak, or faulty idle air control valve.

Our Process

From Code to Confirmed Fix

01

Full Code Scan

We connect to your vehicle's OBD-II port and retrieve all fault codes across every module — engine, transmission, ABS, TPMS, and body systems.

02

Live Data Review

We analyze real-time sensor data and perform component-level tests to verify the fault and rule out secondary causes before recommending a repair.

03

Written Report

You receive a complete report explaining what was found, what it means, and what needs to be done — with a flat-rate repair estimate.

04

Repair & Verify

Once approved, we complete the repair and perform a post-repair scan to confirm all fault codes are cleared and monitors are functioning correctly.

Diagnostic Fee Applied to Repairs

Engine diagnostic service typically ranges from $99–$150. If you choose to complete the repair at AutoTrek, this fee is credited toward the total cost. No work is performed without your written approval, and we never recommend repairs your vehicle doesn't need. Call (303) 328-3356 with any questions.

FAQ

Diagnostics Questions

Engine diagnostic service at AutoTrek typically ranges from $99–$150 depending on the scope of testing required. This fee is credited toward the repair cost if you choose to have the work done with us. We provide a written report of all fault codes and findings before any repair work begins.
A check engine light means your vehicle's onboard computer (ECU) has detected a fault and stored a Diagnostic Trouble Code. The cause can range from a simple loose gas cap or faulty oxygen sensor to serious issues like a misfiring engine or failing catalytic converter. A proper OBD-II scan identifies the exact code and system involved — so you know exactly what you're dealing with.
If the check engine light is solid and the vehicle seems to run normally, you can typically drive a short distance to a shop. If the light is flashing or blinking, it indicates a serious active fault — usually a misfire that can damage the catalytic converter. A flashing CEL means stop driving and have the vehicle inspected or towed immediately.
OBD-II (On-Board Diagnostics, second generation) is a standardized monitoring system built into every vehicle sold in the US since 1996. It continuously monitors engine and emissions systems and stores Diagnostic Trouble Codes when a fault is detected. A professional scan tool connects to the OBD-II port (typically under the dashboard) to retrieve codes and live sensor data for analysis.
Yes. AutoTrek is a full-service repair facility. After diagnosing the issue we provide a written estimate for all recommended repairs. You are never obligated to proceed — but if you do choose to have the repair completed at AutoTrek, the diagnostic fee is applied toward the total service cost.
A basic OBD-II scan and code interpretation takes 15–30 minutes. A comprehensive diagnostic that includes live data analysis, component testing, and inspection of specific systems may take 1–2 hours. We provide a time estimate when you drop off your vehicle and keep you updated throughout the process.

Book an Appointment

Get Answers Today

Stop guessing. Same-day diagnostic appointments available. Call us or submit the form and we'll confirm shortly.

Location

8161 S Grant Way, Littleton, CO 80122

Hours

Mon–Fri: 9:00am – 5:00pm

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