How to Reset Hino Check Engine Light (2026 Update)

This guide is designed to offer valuable insights and practical instructions on how to effectively reset the check engine light in your Hino vehicle. We will delve into the reasons why the check engine light may come on, necessary precautions before initiating a reset, the methods available for resetting the light, a detailed step-by-step guide to follow, testing procedures post-reset, common errors to avoid, and essential maintenance tips for the continued well-being of your Hino vehicle. Join us as we navigate the process of resetting the check engine light in your Hino with clarity and precision.

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Table of Contents

1. What Is the Hino Check Engine Light?

2. Common Reasons the Check Engine Light Comes On

3. Most Common Hino Fault Codes

4. Fault Codes That Require Immediate Repair

5. How to Reset the Hino Check Engine Light

6. Testing the Hino Check Engine Light Reset

7. Preventing Future Issues with the Hino Check Engine Light

8. Frequently Asked Questions

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What Is the Hino Check Engine Light?

The Hino check engine light — also called the Malfunction Indicator Lamp (MIL) — illuminates when the truck's onboard computer (ECU) detects a reading from a sensor or system that falls outside normal operating parameters. It does not tell you what the problem is on its own. A diagnostic scan tool is required to read the stored fault code and identify the root cause.

Modern Hino trucks continuously monitor fuel delivery, air intake, exhaust aftertreatment (DPF, SCR, EGR), transmission, and engine performance. When the ECU logs an abnormal reading, it stores a Diagnostic Trouble Code (DTC) and triggers the MIL.

Solid check engine light: A non-critical fault is present. It is generally safe to complete your current trip, but the vehicle should be diagnosed within 24–72 hours. Do not ignore it.

Flashing check engine light: A severe active fault is present — typically an engine misfire or aftertreatment system failure. Stop the vehicle as soon as safely possible. Continued operation risks catalytic converter damage, DPF damage, or engine failure.

Technician Tip: A solid MIL with reduced power is frequently misdiagnosed as a fuel problem. Before replacing fuel filters or injectors, connect a scan tool and read the codes. Low power with a CEL is very often an SCR, DPF, or EGR derate — not a fuel delivery fault. The power reduction is intentional and controlled by the ECU.

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Common Reasons the Hino Check Engine Light Comes On

The Hino check engine light can be triggered by a wide range of faults — from a loose fuel cap to a failing DPF. The most common causes include:

• Emissions system faults — DPF soot overload, SCR/DEF system issues, EGR valve or cooler failure

• Sensor failures — oxygen sensor, mass airflow sensor, fuel rail pressure sensor, crankshaft or camshaft position sensor

• Fuel system problems — low rail pressure, clogged injectors, failing high-pressure fuel pump

• Wiring and connector faults — damaged harnesses near heat sources, corroded pins, broken circuits

• Loose or damaged fuel cap — causes fuel system pressure faults on applicable models

• Glow plug or air heater relay failure — common on cold-climate trucks, triggers codes during startup cycles

Because many of these faults produce similar symptoms, the only reliable way to identify the cause is to read the stored fault codes using a diagnostic scan tool.

Before You Reset — Read This First

Do not reset the check engine light before diagnosing the fault. Clearing the code without repairing the underlying problem accomplishes nothing. The code will return — often within minutes of driving — and you lose the freeze frame data that shows exactly what conditions triggered the fault.

The correct process is:

1. Connect a scan tool and read all stored fault codes

2. Record every active and pending code before clearing anything

3. Diagnose the root cause of each fault

4. Complete the repair

5. Then clear the codes

With a tool like Jaltest, this process is straightforward. Jaltest allows you to read fault codes across all ECUs, view live engine data, access wiring diagrams, run component tests, and follow guided troubleshooting workflows — all in one platform. This eliminates guesswork and prevents unnecessary parts replacement.

Technician Tip: Shops that clear codes without diagnosing first waste time and money. Freeze frame data disappears the moment you clear the code. That data — engine speed, load, coolant temperature, rail pressure at the moment of the fault — is often the fastest path to the correct diagnosis.

Most Common Hino Fault Codes

The table below covers the most frequently reported Hino fault codes. Aftertreatment system codes (DPF, SCR, EGR) account for approximately 60% of check engine light complaints on post-2010 Hino trucks.

Fault Code	Description	Severity	Most Common Cause	Typical Repair
P0335	Crankshaft Position Sensor Circuit	Critical	Damaged wiring near flywheel housing; failed sensor	Inspect harness first; replace sensor if wiring is good
P0340	Camshaft Position Sensor Circuit	Critical	Failed CMP sensor; timing chain wear	Replace sensor; check timing chain condition
P0201–P0206	Injector Circuit Malfunction (Cylinders 1–6)	High	Failed injector solenoid; wiring short or open	Test injector resistance; repair wiring or replace injector
P0087	Fuel Rail Pressure Too Low	High	Clogged fuel filter; failing HP pump; leaking injector return	Replace fuel filter first; then test HP pump output
P0191	Fuel Rail Pressure Sensor Performance	High	Failed sensor; actual low pressure condition	Verify with known-good sensor; repair or replace
P0401	EGR Flow Insufficient	Moderate	Clogged EGR valve; blocked EGR cooler; failed position sensor	Clean or replace EGR valve; inspect EGR cooler
P0402	EGR Flow Excessive	Moderate	EGR valve stuck open; failed position sensor	Clean or replace EGR valve; test position sensor
P2002	DPF Efficiency Below Threshold	High	DPF ash-loaded; failed DPF; excessive short-trip driving	Forced regeneration first; replace DPF if regeneration fails
P20EE	SCR NOx Catalyst Efficiency Below Threshold	High	Low DEF quality; faulty NOx sensor; degraded SCR catalyst	Drain and refill DEF; test NOx sensors; replace SCR if needed
P0510	Accelerator Position Sensor / Idle Switch	Moderate	Faulty APP sensor; damaged wiring; dirty contacts	Clean connector; test voltage output; replace if out of range
P0101	Mass Airflow Sensor Range/Performance	Moderate	Contaminated MAF element; intake leak; air filter bypass	Clean MAF sensor; inspect intake system for leaks
P0113	Intake Air Temperature Sensor High Input	Low	Failed IAT sensor; open circuit in wiring	Test sensor resistance; replace if needed
P0128	Coolant Temperature Below Thermostat Range	Low	Thermostat stuck open; failed ECT sensor	Replace thermostat; verify ECT sensor accuracy
P0541	Intake Air Heater Relay Circuit Low	Moderate	Failed glow plug relay; open circuit; failed glow plugs	Test relay operation and glow plug resistance
P0641 / P0651	Sensor Reference Voltage Circuit Open	High	ECM supply fault; wiring short to ground on 5V reference circuit	Trace 5V reference circuit and isolate shorted sensor

Can I keep operating?

• Critical codes (P0335, P0340, P0641): No. Stop and diagnose immediately.

• High codes (P2002, P20EE, P0087): No. Derate is active or engine damage risk is present.

• Moderate codes (P0401, P0101, P0510): Short distances only. Diagnose within 48 hours.

• Low codes (P0113, P0128): Yes, but schedule repair at next service.

Technician Tip — most wasted parts on Hino trucks:

• EGR valves replaced for P0401 when the EGR cooler is actually blocked. Always test EGR cooler differential pressure before ordering a valve.

• DPF pressure sensors replaced when the DPF itself is ash-loaded. Run a forced regen and monitor soot load first.

• Fuel injectors replaced for P0201–P0206 when the fault is a wiring resistance issue. Measure injector solenoid resistance (typically 0.4–2 ohms) before ordering parts.

• NOx sensors replaced for P20EE when contaminated DEF is the actual cause. Drain and refill DEF before condemning any sensor.

Fault Codes That Require Immediate Repair

Stop operating the vehicle immediately if any of the following are active. Continued operation risks multiplying repair costs by 5–10x.

Stop immediately — Critical:

• P0335 / P0340 — Crank/cam sensor failure (stall or no-start risk)

• P0641 / P0651 — 5V reference voltage loss (cascading sensor failures)

• U0100 / U0101 — CAN bus failure

• Any code accompanied by a flashing MIL

• Any CEL combined with an oil pressure or coolant temperature warning

Repair within 24–48 hours — High:

• P2002 — DPF efficiency (active derate)

• P20EE — SCR NOx efficiency (active derate)

• P0087 — Fuel rail pressure low

• P0201–P0206 — Injector circuit faults

• P0191 — Fuel pressure sensor

Repair within 1 week — Moderate:

• P0401 / P0402 — EGR flow faults

• P0101 — MAF sensor performance

• P0510 — APP sensor idle switch

• P0541 — Air heater relay

Schedule at next service — Low:

• P0113 — IAT sensor

• P0128 — Coolant temp below threshold

• P0133 — O2 sensor slow response

How to Reset the Hino Check Engine Light

There are two methods: scan tool reset (always recommended) and the manual key-cycle procedure (limited use only).

Method 1: Scan Tool Reset (Recommended)

This is the only method that confirms the fault has actually been resolved.

1. Connect your diagnostic adapter to the OBD-II port. Turn ignition to ON — do not start the engine.

2. Launch your scan tool software (Jaltest, Autel, or Hino-DX III). Select the vehicle and navigate to the Engine ECU and Aftertreatment ECU.

3. Read all stored fault codes. Record every active and pending code before clearing anything.

4. Diagnose and repair the root cause of every active fault code.

5. After repair, use the scan tool to clear fault codes from all relevant ECU modules: Engine, Aftertreatment, Transmission.

6. Start the engine and verify the MIL does not return. Perform a short test drive under the conditions that originally triggered the fault.

7. Re-scan after the test drive to confirm no pending codes have set.

Method 2: Manual Key-Cycle Procedure (Limited Use)

Use this only when a scan tool is not available. This method may reset minor, non-critical codes on some Hino models. It will not clear DPF, SCR, or aftertreatment codes. It does not confirm the fault has been fixed.

1. Turn the ignition key to ON. Do not start the engine. Allow all dashboard lights to illuminate fully.

2. Fully depress and release the accelerator pedal 5 times quickly (within 5 seconds).

3. Depress and release the accelerator pedal 8 more times.

4. Cycle the ignition key: OFF → ON → OFF → ON → OFF → ON (5 total cycles, ending in the ON position).

5. Fully depress the accelerator pedal 5 times, then press the brake pedal 3 times.

6. Turn the ignition off. Wait 30 seconds, then restart and check the dashboard.

Note: If the check engine light returns within one drive cycle, an unresolved fault code is still present. A scan tool is required. Do not repeat the key-cycle reset — it does not fix the underlying problem.

Testing the Hino Check Engine Light Reset

After performing either reset method, verify the repair was successful before returning the vehicle to service.

1. Start the engine and observe the dashboard. The check engine light should not illuminate.

2. Listen for unusual engine sounds — knocking, rough idle, misfires, or abnormal exhaust.

3. Let the engine idle for 5–10 minutes. Monitor for the light returning at idle.

4. Take the truck for a test drive and replicate the conditions that originally triggered the fault — similar load, speed, and operating temperature.

5. After the test drive, re-scan the vehicle with your diagnostic tool to confirm no pending or active codes have set.

If the light returns during the test drive, the root cause has not been fully resolved. Do not clear the code again — diagnose further.

Preventing Future Issues with the Hino Check Engine Light

Many Hino check engine light problems can be prevented through regular maintenance and early diagnostics. The following practices help keep fault codes from appearing in the first place.

• Perform regular maintenance on schedule. Oil changes, air filter replacements, and fuel system servicing keep sensors reading correctly and reduce the likelihood of fault conditions developing.

• Inspect sensors and wiring regularly. Damaged wiring and corroded connectors are among the most common causes of Hino fault codes. Check harness routing near exhaust components and chassis edges where chafing is most likely.

• Maintain proper fluid levels. Engine oil, coolant, DEF, and transmission fluid all affect sensor readings. Low DEF is one of the most common triggers for SCR and NOx system faults.

• Address warning signs early. Changes in fuel economy, smoke colour, idle quality, or throttle response often precede a check engine light. Diagnosing early is always cheaper than waiting for a derate or shutdown.

• Use diagnostic scans as part of routine maintenance. Periodic scans can detect stored pending codes and sensor irregularities before they become active faults. Catching a P0401 before it escalates to a full EGR failure saves significant repair time and cost.

• Use high-quality DEF. Contaminated or diluted DEF is one of the top causes of P20EE and SCR-related derates. Always use DEF that meets ISO 22241 specification and store it properly.

Conclusion

In conclusion, resetting the Hino check engine light is a straightforward process that can be done with the right tools and knowledge. You can keep your Hino vehicle running smoothly and efficiently by understanding the reasons for the light to illuminate, taking necessary precautions, following the correct reset methods, and staying proactive with maintenance. Remember that the check engine light is a valuable indicator of potential issues, and addressing them promptly is essential for the health of your vehicle. Thank you for reading our comprehensive guide on resetting the Hino check engine light.

Want some more information about pricing details and packages? Download our 2026 Jaltest pricing guide!

Frequently Asked Questions

How do I reset a Hino check engine light without a scan tool?

A manual key-cycle procedure (accelerator pedal cycling with ignition on) may reset minor codes on some Hino models. However, it does not work for aftertreatment codes (DPF, SCR, EGR), it does not identify the root cause, and it provides no confirmation the problem is resolved. A scan tool is always the correct method.

Will a Hino check engine light reset on its own?

Yes, the Hino check engine light can reset on its own, but it depends on what caused the warning light.

In many cases, the Hino check engine light will reset on its own after the underlying problem has been fixed. The vehicle’s onboard diagnostic system continuously monitors engine performance, and if it no longer detects the fault, the light may turn off automatically after several normal driving cycles.

However, this doesn’t always happen immediately. Some Hino trucks require multiple ignition cycles or several hours of operation before the system clears the warning light. In other situations, the diagnostic trouble code (DTC) remains stored in the engine control unit (ECU), meaning the check engine light may stay on until the code is cleared with a diagnostic scanner.

What scan tool works best for Hino trucks?

We recommend either Autel or Jaltest for most Hino truck owners. Both offer endless brand support, which makes them great choices for multi-brand fleets.

• Autel is an affordable and user-friendly diagnostic tool which possesses limited OEM capabilities. It is capable of ECU coding, bi-directional control, DPF-related functions. Autel can effectively support non-standard OBD trucks like Hino.

• On the more expensive side is Jaltest, with comprehensive OEM functionalities, you can skip going back and forth with the dealership by using Jaltest’s dealer-level capabilities. It works excellently with Hino trucks.

Is it safe to drive a Hino with the check engine light on?

It may be okay to drive a Hino with the check engine light on. For how long it can be driven and whether it’s safe depends on the light's behavior.

• A solid CEL is usually a non-critical issue, such as a loose gas cap or faulty O2 sensor. It's safe to drive short distances but should be diagnosed and repaired soon to prevent long-term damage or decreased fuel efficiency.

• A flashing CEL signals a severe problem like an engine misfire, which could damage the catalytic converter or DPF. Driving is unsafe, and the vehicle should be towed immediately. Ignoring critical codes can lead to engine damage, increased fuel consumption, and emissions compliance issues.

• Generally, when the check engine light comes on:

  • Check for obvious issues

  • Scan for codes using a diagnostic tool like Jaltest

  • Assess the urgency based on the severity of the codes.

What are common fault codes for Hino trucks?

Three common fault codes we see are:

1. P0335: Caused by main ICE rotation rate sensor or its wiring.

2. P0201-P0203: 201-203 indicate an issue with a cylinder nozzle. 201 means the issue is in the first cylinder, 202 the second cylinder, and 203 the third cylinder.

3. P0510: The accelerator switch is malfunctioning.

If you come across any of these fault codes, you should get the vehicle serviced or troubleshoot the issuewith a diagnostic tool immediately.

You can read the full Hino fault code list here.

Does a Hino check engine light always cause a derate?

No. Only specific codes trigger a derate — primarily aftertreatment codes like P2002 (DPF) and P20EE (SCR). Sensor codes like a faulty IAT sensor or coolant temp code typically do not cause a power derate. Connect a scan tool to confirm whether a derate protection mode is active.