P2610 on 2014-2016 Lexus GX460: Engine Off Timer Fixes & TSB Explained

What's Unique About the 2014-2016 Lexus GX460

For this specific generation of Lexus GX460, the P2610 code is a well-documented issue. Lexus acknowledged it as a software logic problem and issued a Technical Service Bulletin (TSB L-SB-0026-16) with a direct fix. Unlike in other vehicles where this code might lead to a complex diagnosis of wiring, batteries, or component failure, the cause on the GX460 is almost certainly 🎬 Watch: Understanding the P2610 code and common engine timer fixes the ECM software needing an update. This makes the diagnosis straightforward and points directly to a dealership reflash as the solution. The TSB explicitly states the ECM should NOT be replaced for this condition.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on.
• Inability to pass an emissions test because readiness monitors will not complete.
• In rare cases, erratic behavior of systems that rely on the engine-off timer, though this is not commonly reported for the GX460.

Most Likely Causes

1. Outdated Engine Control Module (ECM) Software 🔴 High Probability → Shop Engine Control Module (ECM) Lexus officially identified a logic flaw in the original ECM software for 2014-2016 models and issued TSB L-SB-0026-16 to correct it.
   How to confirm: A Lexus dealership can use Techstream software to check the vehicle's current software calibration ID and compare it to the updated versions listed in the TSB. For 2014-2015 models, the new ID is 89661-60W12. For 2016 models, the new ID is 89661-60U21.
   Typical fix: Flash reprogram the ECM with the updated software provided by Lexus. The TSB specifies this is a 0.4-hour labor operation. The dealer must also affix an "Authorized Modifications" label (P/N 00451-00001-LBL) under the hood to show the update was performed.
   Est. part cost: $0
2. Weak or Failing Battery ⚪ Low Probability → Shop Vehicle Battery Low system voltage during engine shutdown can cause various electronic modules, including the ECM's internal timer, to behave erratically or lose memory. An owner on a Reddit forum reported the code appeared when their battery tested at a very low 2.6V, and another on ClubLexus noted the link.
   How to confirm: Test the battery's voltage and cranking amps. A healthy battery should read above 12.4 volts at rest. During reprogramming, the TSB requires maintaining voltage at 13.5V, indicating the system's sensitivity to low voltage. A professional load test is recommended.
   Typical fix: Replace the vehicle's 12V battery.
   Est. part cost: $150-$350
3. Faulty Engine Control Module (ECM) ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This is a diagnosis of exclusion. If the ECM software is confirmed to be up-to-date per TSB L-SB-0026-16 and the battery/charging system are healthy, but the code persists, the ECM itself may have an internal hardware fault.
   Typical fix: Replace the Engine Control Module. This is a last resort and must be programmed to the vehicle. The TSB explicitly warns against this as the first step.
   Est. part cost: $1014-$1205

Diagnosis Steps

1. Scan the vehicle for codes to confirm P2610 is present and not accompanied by other codes that might suggest a different root cause.
2. Check for the presence of an 'Authorized Modifications' label under the hood, which would indicate if the ECM has already been updated per the TSB.
3. If no label is present, take the vehicle to a Lexus dealership to perform the software update as outlined in TSB L-SB-0026-16. This repair is covered under the Lexus Federal Emission Warranty (96 months or 80,000 miles, whichever comes first from the in-service date).
4. If the software is already up-to-date or the code returns after the update, perform a comprehensive test of the vehicle's 12V battery and charging system to rule out voltage issues.
5. Inspect the ECM's power and ground connections for any signs of corrosion or damage, although this is an unlikely cause.
6. If all other steps fail, suspect a hardware failure within the ECM itself, which would then require replacement.

Parts You'll Likely Need

• ECM Software Update (OEM #New Calibration IDs: 89661-60W12 (2014-15), 89661-60U21 (2016)) — This is not a physical part, but a software reflash that corrects the logic flaw causing the P2610 code, as specified by Lexus TSB L-SB-0026-16.
  Trusted brands: Lexus
  OEM price range: $0-$250
  Aftermarket price range: N/A

Technical Service Bulletins (TSBs) & Recalls

• L-SB-0026-16: Issued June 23, 2016, for 2014-2016 GX460s. Details the MIL 'ON' with DTC P2610, states the cause is ECM logic, and provides new calibration IDs to fix it. Specifies a 0.4-hour labor time and coverage under the Federal Emission Warranty (96 mo/80k mi).

Platform-Specific Known Issues

• A Technical Service Bulletin (L-SB-0026-16) was issued specifically for 2014–2016 GX460 models to address this code. The fix involves reprogramming the ECM with modified logic.
• The repair is explicitly covered by the Lexus Federal Emission Warranty for 96 months or 80,000 miles from the vehicle's in-service date.

Mechanic-Grade Diagnostic Values

• System Voltage During ECM Reflash — expected: 13.5 Volts. Failure: Voltage below 13.5V can cause the reflash to fail or corrupt the ECM.
• ECM Power Supply (VC Output Circuit) — expected: 5 Volts. Failure: A short in the VC circuit will cause the voltage to drop, preventing the ECM microprocessor and related sensors from operating.
• Battery Voltage at ECM Connector (Engine Off) — expected: Above 12.2 Volts. Failure: Persistent low voltage can indicate a failing battery or a parasitic drain, which can cause erratic module behavior including the P2610 code.

Scan Tool Commands That Help

• Techstream: Health Check — This is the first step to automatically check all vehicle ECUs. It will display a 'Yes' link in the 'Cal. Update?' column if a newer software calibration is available for the ECM, directly indicating if the TSB applies.
• Techstream: Calibration Update Wizard (CUW) — 🎬 See how to use TechStream for ECU programming and settings This application is used to perform the actual flash reprogramming of the ECM with the new software file specified in TSB L-SB-0026-16.
• Techstream: Utility / All Readiness — After a repair attempt, this function can be used to check the status of the emissions readiness monitors to confirm the fix has allowed the internal self-tests, which depend on the engine-off timer, to complete successfully.

Wiring & Ground Locations

• ECM — Located on the right side of the dashboard, typically behind the glove compartment.. If the TSB reflash does not fix the code, checking for clean, tight power and ground connections at the ECM connector is the next logical step before condemning the module.
• Ground Point C4 — Located on the left side of the engine.. This is one of the primary engine-area ground points. A corroded or loose ground here can cause various electrical issues, potentially affecting the ECM's stability, although it's a rare cause for P2610.
• J/C A55, A57 — Junction Connectors located in the left rear and engine room R/B assembly, respectively.. These connectors are part of the ground distribution circuit. A fault within these junctions could interrupt a stable ground path to the ECM.

Real Owner Repair Stories

• ClubLexus user 'robd88' (Lexus GS (4th Gen)) — Check Engine Light with code P2610.
  ✅ What actually fixed it The user tested the car battery and found it was bad. Replacing the battery and clearing the code resolved the issue, suggesting the low voltage was the root cause.
• IH8MUD.com user 'ElJayBird' (2014 Toyota Land Cruiser (Platform Mate)) — TRAC OFF, Check Engine Light, and flashing 4LO light with code P2610 stored.
  ✅ What actually fixed it The user took the vehicle to a dealership, which identified a TSB for the issue. The dealership performed an ECU flash, which resolved the code. The user was initially charged for the service but questioned if it should have been covered by warranty.

OEM Part Supersession History

• 360Q9000, 360Q9100 (for 2014-2015 models) → 360Q9200 (Calibration ID) — Software logic was modified to reduce the possibility of the ECM/PCM Engine OFF Timer Performance issue.
  Heads up: These are software calibration IDs, not physical parts. The new calibration file (leading to part number 89661-60W12) must be flashed onto the ECM.
• 360X8000 (for 2016 models) → 360X8100 (Calibration ID) — Software logic was modified to reduce the possibility of the ECM/PCM Engine OFF Timer Performance issue.
  Heads up: These are software calibration IDs, not physical parts. The new calibration file (leading to part number 89661-60U21) must be flashed onto the ECM.

Model Year Variations Within This Range

• 2014-2015 vs 2016: The TSB L-SB-0026-16 specifies different new software and calibration IDs for these two groups. 2014-2015 models receive a new ECM part number of 89661-60W12 (with calibration ID 360Q9200), while 2016 models receive part number 89661-60U21 (with calibration ID 360X8100).