2027 Toyota Grand-Highlander Check Engine Light

A steady light means a stored fault, while a flashing light indicates a severe misfire per OBD-II standards.

Your Grand Highlander’s engine computer logs a diagnostic trouble code (DTC) when a system falls outside expected parameters. Common triggers range from a loose gas cap (EVAP leak) to sensor faults or misfires. Our Peoria Toyota technicians retrieve codes, review freeze‑frame data, and confirm root cause with guided testing, not just a quick scan. You can schedule an appointment online anytime.

• Steady light: drive cautiously and book diagnostics soon
• Flashing light: stop driving to prevent catalytic converter damage
• OBD-II code points to the affected system for targeted testing

Frequent causes include EVAP leaks (loose gas cap), O2 sensor faults, MAF issues, misfires, and catalytic converter efficiency codes.

On the Grand Highlander, these categories cover many real-world DTCs we see across the Phoenix metro. Each code can have multiple underlying causes, so confirmation testing matters. Our Toyota scan tools access manufacturer data that generic readers miss, helping isolate the exact fault. See current service specials before you schedule service.

• EVAP small/large leak: check cap seal and system integrity
• O2 sensor aging: affects fuel trim and emissions readiness
• Misfire codes: can overheat and damage the catalytic converter

Yes if the light is steady, but stop driving if it’s flashing to avoid catalytic converter damage.

A steady light signals a non-urgent fault; minimize trips and book diagnostics promptly. A flashing light flags an active misfire that can overheat the catalyst and raise repair costs. Larry H. Miller Toyota Peoria can scan your Grand Highlander and provide a written estimate before any repair. Use our online tool to schedule service now.

• Steady light: reduce load, avoid towing, and schedule soon
• Flashing light: pull over safely; arrange towing to our Peoria service center
• We serve Peoria, Glendale, Surprise, Sun City, Avondale, Scottsdale, Phoenix

A parts store reads the code, but a dealer diagnoses the cause using Toyota factory data and isolation testing.

One DTC can have multiple root causes; replacing parts based on a generic code pull risks misdiagnosis. Our OEM-certified technicians access manufacturer live data, test plans, and service bulletins specific to your Grand Highlander. You’ll get confirmed results and a written estimate before any repair. Check service specials and schedule an appointment.

• Factory scan tools and guided diagnostics for Toyota systems
• Pinpoint testing to avoid unnecessary parts
• Documented findings with next-step recommendations

No—clearing codes resets readiness monitors, and most emissions tests fail vehicles with incomplete monitors.

After a reset, your Grand Highlander must complete specific drive cycles to set readiness. If the underlying issue remains, the light may return and the test will fail. We fix the root cause, confirm monitors, and provide documentation you can bring to testing. Book diagnostics via our online scheduler.

• Readiness monitors must complete before testing
• We verify repairs with live data and test drives
• Written results support a smoother retest

A flashing light means an active misfire that can overheat and damage the catalytic converter.

Misfires dump unburned fuel into the exhaust, rapidly raising catalyst temperatures. Continued driving can turn a simple ignition or fuel fix into an expensive emissions repair. Safest action: reduce speed, avoid hard acceleration, and arrange service at Larry H. Miller Toyota Peoria. You can schedule now and review service specials.

• Stop driving if flashing persists
• Potential ignition coil, plug, injector, or compression issue
• Prompt diagnosis prevents catalytic converter damage

Our process starts with an OBD-II scan on your 2027 Toyota Grand Highlander and a review of freeze‑frame data to confirm the conditions that set the code. Next, a Toyota-trained technician performs isolation testing—visual inspections, smoke tests for EVAP leaks when applicable, circuit checks, and live data analysis using factory scan tools. We then verify symptoms with a controlled test drive, correlate findings to Toyota service information, and rule out related faults. You receive clear results and a written estimate before any repair is performed. Ready to proceed or just need definitive answers? Use our online tool to schedule service with Larry H. Miller Toyota Peoria.

Larry H. Miller Toyota Peoria provides code-specific diagnostics for the 2027 Toyota Grand Highlander across the Phoenix West Valley and Greater Phoenix metro area, including Peoria, Glendale, Surprise, Sun City, Avondale, Scottsdale, and Phoenix. Factory Toyota scan tools reveal proprietary data that generic readers can’t, helping pinpoint issues like EVAP leaks, O2 sensor aging, MAF drift, or intermittent misfires. After testing, we explain what failed, why it failed, and the repair options, then document the plan in writing. Visit us at 8633 W Bell Rd, Peoria, AZ 85382, or schedule your appointment online. You can also review our Service Center resources at Service Center for helpful information.

Drivers of the 2027 Toyota Grand Highlander most often encounter codes such as P0442/P0455 (EVAP small/large leak), P0138/P0158 (O2 sensor high voltage), P0101 (MAF range/performance), P0300–P0306 (random/single-cylinder misfires), and P0420 (catalyst efficiency). EVAP leaks may be as simple as a loose or cracked gas cap, but ignoring them can keep emissions monitors incomplete and trigger test failures. Misfire codes left unchecked can overheat and damage the catalytic converter, raising repair costs. Catalyst efficiency faults can stem from upstream issues, so accurate testing prevents unnecessary parts replacement. Bring your 2027 Toyota Grand Highlander to Larry H. Miller Toyota Peoria in Peoria for an accurate diagnosis — schedule service.