P1491Manufacturer-specific code

P1491 Code: EGR Valve Insufficient Lift (Honda)

On Honda and Acura vehicles, the P1491 code means the EGR valve is not lifting far enough. You may notice hesitation or light pinging under load. On other brands the same number means something else.

Severity
Medium
Can I keep driving?
Yes, no immediate risk
Estimated cost
$40 to $450
Difficulty
Medium
System
Emissions Control
Applies to
Depends on the manufacturer

Common in: Dodge, Honda, Jeep

Updated Reviewed by Renzo Chacca

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What the P1491 code means

P1491 is a manufacturer-specific code: the 1 in the second position means each automaker defines what it means, not the generic SAE standard. That is why the same number means different things depending on the vehicle, as the table shows. This page focuses on the Honda and Acura meaning.

ManufacturerMeaning of P1491
Honda and AcuraEGR valve insufficient lift
Chrysler, Dodge, Jeep and RamRadiator fan control relay circuit

Many Hondas have an electric EGR valve with a sensor that measures how far it opens. The computer compares the commanded opening with the actual one.

The computer sets the P1491 code when the valve does not open far enough. The cause is almost always carbon in the valve or in the manifold passages.

Before you start repairs, confirm the make, model, year and engine. With manufacturer codes, the same number can change even between engines from the same brand.

P1491 code symptoms

  • Check engine light on.
  • Hesitation or light pinging under load.
  • Usually no symptoms at idle.

Likely causes of the P1491 code

  1. Carbon in the EGR valve. The most frequent cause.
  2. Plugged EGR passages in the manifold. Confirm it with the tests in the diagnosis section.
  3. Failed EGR valve. Check it by commanding it with the scan tool.
  4. Connector. Check the lock tab, the pins and any sign of moisture or corrosion.

How to diagnose the P1491 code step by step

  1. Command the EGR with the scan tool and watch the lift sensor.
  2. Remove and clean the valve and check that it moves freely.
  3. Clean the manifold passages of carbon.

How to fix the P1491 code

  • Clean the valve and the passages.
  • Replace the valve if it does not move.

Technical reference data

  • The lift sensor gives a 0.5 to 4.5 V signal depending on how far the valve opens.
  • P1xxx codes are manufacturer-specific: confirm the definition with a scan tool that supports your brand.
  • Reference values: check the manufacturer data for your vehicle.

Brand-specific notes

On Hondas, carbon is the usual story here, so cleaning the valve and the passages comes before buying a new valve.

P1491 on Honda

Very common on the Civic, Accord, CR-V, Fit and Odyssey.

P1491 on Chrysler

Chrysler, Dodge, Jeep and Ram use the same number for a radiator fan control relay circuit fault, which is a different problem.

If your vehicle is another brand, check the table above for the meaning its manufacturer gives this code and confirm it with a compatible scan tool.

Frequently asked questions about P1491

What does the P1491 code mean on a Honda?
It means the EGR valve has insufficient lift. You may notice hesitation or light pinging under load.
Does P1491 mean the same thing on every brand?
No. On Chrysler it means a radiator fan control relay circuit fault. Always confirm the definition for your make.
Can I drive with a P1491 code?
Yes, in most cases. With a P1491 code severity is medium, so watch for pinging under load and get it checked soon.
How much does it cost to fix P1491?
Roughly $40 to $450 on a Honda. Cleaning the valve and passages is at the low end, and a new valve costs more.
Will a P1491 code clear itself?
Not while carbon is still limiting the valve. After cleaning or replacing it, clear the code and confirm it does not return.
What is the most common cause of P1491?
Carbon in the EGR valve is the most frequent cause. Plugged passages in the manifold come next.

Related codes

Questions about the P1491 code

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