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P0605 on Toyota Highlander

Internal Control Module Read Only Memory (ROM) Error

Factory diagnostic protocol and troubleshooting wire for fault code P0605 specifically for the Toyota Highlander (2020–2026, 2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid).

Verified OEM Telemetry & Field Repair Tree
Toyota Highlander2020–2026
Toyota Highlander
SUV2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
Highlander SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Not Recommended
Critical urgency level
Est. Repair Cost
$350 - $1,200
Parts & Labor DIY
Check P0605 On Another Toyota Model:
Diagnose P0605 on Specific Highlander Model Year:

1. Symptoms of P0605 on Toyota Highlander

When the Engine Control Module (ECM/PCM) on your Toyota Highlander (2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid) logs fault code P0605, drivers commonly observe:

Check Engine Light on on Toyota Highlander (2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid)
Engine stalls or enters limp mode on Toyota Highlander (2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid)
Failure to pass emissions on Toyota Highlander (2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid)
Toyota Highlander OBD-II Port Location
The 16-pin diagnostic connector is located Under driver steering column near kick panel. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Toyota Highlander

Historical warranty claims and technical repair bulletins for Toyota Highlander point to the following failure distribution:

55%
Corrupted ECM firmware (Toyota OEM Part)
25%
Failed internal ROM chip in ECM (Toyota OEM Part)
12%
Faulty aftermarket tuning chip / flash (Toyota OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for Toyota Highlander.

3. Step-by-Step DIY Repair Guide for Toyota Highlander

01
Scan and Record Freeze Frame Telemetry

Connect an OBD-II scan tool and record freeze frame sensor telemetry for code P0605 to note engine RPM, load, and voltage when the fault triggered. on the Toyota Highlander equipped with 2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid.

Required Tool: OBD-II Scanner
02
Inspect Related Wiring Harness & Connectors

Inspect the electrical connector and wiring harness related to P0605 for chafing, corrosion, moisture, or pin push-out. on the Toyota Highlander equipped with 2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid.

Required Tool: Flashlight, Multimeter
03
Test Component Resistance & Voltage Supply

Measure circuit voltage supply (12V B+ or 5V reference) and sensor/actuator resistance according to factory repair manual specifications. on the Toyota Highlander equipped with 2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid.

Required Tool: Digital Multimeter
04
Replace Defective Component

Install a new OEM-grade replacement part, torque fasteners to factory spec, and ensure electrical locking tabs click firmly. on the Toyota Highlander equipped with 2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid.

Required Tool: Hand Tool Socket Set, Torque Wrench
05
Clear Trouble Codes & Complete Drive Cycle

Clear all stored DTCs from vehicle memory and perform an OBD-II drive cycle to confirm the diagnostic monitor resets to 'Ready'. on the Toyota Highlander equipped with 2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid.

Required Tool: OBD-II Scanner
Recommended Parts & Testing Tools

Equipment for Diagnosing Toyota Highlander (P0605)

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Direct-Fit Replacement Part

Toyota Highlander OEM Replacement Sensor

4.7 / 5.0 (Verified Fit)

Direct-fit replacement assembly engineered to OEM tolerances for Toyota Highlander.

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Sensor Signal Voltage Meter

AstroAI Auto-Ranging Digital Multimeter

4.6 / 5.0 (Best Seller)

Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.

$29.99 Prime
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Top Mobile OBD-II Scanner

BlueDriver Bluetooth Pro OBDII Scan Tool

4.7 / 5.0 (50,000+ Reviews)

Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.

Compare OEM & Aftermarket Replacement Sensors for Toyota HighlanderVerified direct-fit pricing from Denso, Bosch, Motorcraft, and ACDelco on Amazon.
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Other Common Fault Codes on Toyota Highlander

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Toyota Highlander:

4. Toyota Highlander P0605 FAQs

What causes code P0605 to trigger on a Toyota Highlander?

On the Toyota Highlander (2.4L Turbo 4-Cyl (T24A-FTS 265HP) / 3.5L V6 / 2.5L Hybrid), P0605 is most frequently caused by Corrupted ECM firmware or Failed internal ROM chip in ECM.

Where is the OBD-II port located on my Toyota Highlander?

On the Toyota Highlander, the 16-pin DLC diagnostic connector is located Under driver steering column near kick panel. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my Toyota Highlander with code P0605?

No. ECM internal memory checksum failure. Given that P0605 carries a Critical severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.