AutoCodes – Isuzu – P1491 Isuzu

P1491 Isuzu Code - Exhaust Gas Recirculation Valve Insufficient Lift

Quick Answer

The exhaust gas recirculation (EGR) system reduces oxides of nitrogen (NOx). Common causes include Exhaust Gas Recirculation Valve harness is open or shorted, Exhaust Gas Recirculation Valve circuit poor electrical connection, Faulty Exhaust Gas Recirculation Valve. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P1491 Isuzu indicates Exhaust Gas Recirculation Valve Insufficient Lift.
Common causes: Common causes include Exhaust Gas Recirculation Valve harness is open or shorted, Exhaust Gas Recirculation Valve circuit poor electrical connection, Faulty Exhaust Gas Recirculation Valve.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 3,132

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 25, 2019

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1491 Isuzu Description

The exhaust gas recirculation (EGR) system reduces oxides of nitrogen (NOx). NOx is generated by high combustion temperatures.
The EGR system lowers peak combustion temperature by recirculating inactive exhaust gas into the air/fuel mixture, thus reducing NOx emissions.
The EGR valve position sensor is built into the EGR valve and detects the amount of valve lift. The command value for the target valve lift is previously stored in the Powertrain Control Module (PCM) so that exhaust gas recirculation can be optimized according to driving conditions.
Comparing this command value with the EGR valve position sensor output signal value, the PCM controls the EGR valve to make the amount of actual valve lift equal to the command value.
If the EGR valve position sensor output signal value differs greatly from the command value in the PCM memory for a set period of time, the EGR valve or the EGR valve position sensor is considered faulty and a DTC is stored.

OBDII Code P1491 Isuzu - Exhaust Gas Recirculation Valve Insufficient Lift - AutoCodes.com — P1491 Isuzu Code - Exhaust Gas Recirculation Valve Insufficient Lift

What does this mean?

What are the Possible Causes of the DTC P1491 Isuzu?

Exhaust Gas Recirculation Valve harness is open or shorted
Exhaust Gas Recirculation Valve circuit poor electrical connection
Faulty Exhaust Gas Recirculation Valve
Exhaust Gas Recirculation Valve clogged
Exhaust gas leaks

How to Fix the DTC P1491 Isuzu?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1491 Isuzu code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1491 Isuzu Code

1. What are the common symptoms of OBDII code P1491 (Isuzu) related to Exhaust Gas Recirculation (EGR) valve insufficient lift?

The common symptoms include rough idling, engine stalling, decreased fuel efficiency, and the illumination of the check engine light.

2. What are the potential causes of OBDII code P1491 (Isuzu) indicating Exhaust Gas Recirculation (EGR) valve insufficient lift?

Possible causes include a faulty EGR valve, clogged EGR passages, a malfunctioning EGR solenoid, or a problem with the EGR sensor.

3. How can I diagnose the issue causing OBDII code P1491 (Isuzu) for Exhaust Gas Recirculation (EGR) valve insufficient lift?

Diagnosis typically involves checking the EGR valve for proper operation, inspecting the EGR passages for blockages, testing the EGR solenoid, and verifying the EGR sensor readings.

4. What are the repair options for resolving OBDII code P1491 (Isuzu) related to Exhaust Gas Recirculation (EGR) valve insufficient lift?

Repairs may involve cleaning or replacing the EGR valve, clearing any blockages in the EGR passages, replacing the EGR solenoid, or addressing any issues with the EGR sensor.

5. Can OBDII code P1491 (Isuzu) for Exhaust Gas Recirculation (EGR) valve insufficient lift cause damage to the engine if left unresolved?

Continued driving with this issue may lead to poor engine performance, reduced fuel economy, and potential damage to the catalytic converter over time.

6. How critical is it to address OBDII code P1491 (Isuzu) for Exhaust Gas Recirculation (EGR) valve insufficient lift promptly?

It is recommended to address this code promptly to prevent further engine performance issues and potential damage, as well as to ensure compliance with emissions regulations.

7. Are there any preventive maintenance measures to avoid encountering OBDII code P1491 (Isuzu) related to Exhaust Gas Recirculation (EGR) valve insufficient lift?

Regularly scheduled maintenance, including cleaning or replacing the EGR valve when necessary, can help prevent issues leading to this code.

8. Can a DIY enthusiast with basic automotive knowledge tackle the repair for OBDII code P1491 (Isuzu) regarding Exhaust Gas Recirculation (EGR) valve insufficient lift?

Depending on the specific cause, some repairs related to this code can be tackled by individuals with basic automotive knowledge, but more complex issues may require professional assistance.

9. Will resetting the OBDII system clear the code P1491 (Isuzu) for Exhaust Gas Recirculation (EGR) valve insufficient lift?

Resetting the OBDII system may temporarily clear the code, but if the underlying issue causing the code is not addressed, it is likely to reappear after driving the vehicle for a certain period.

10. Is it advisable to continue driving the vehicle with OBDII code P1491 (Isuzu) indicating Exhaust Gas Recirculation (EGR) valve insufficient lift?

It is not recommended to continue driving the vehicle with this code illuminated, as it may lead to performance issues and potential damage to engine components.