How To Test The EGR Valve (1990-1993 3.1L V6 Buick Regal, Oldsmobile Cutlass Supreme)

If an EGR diagnostic trouble code is illuminating the check engine light, this is the tutorial you need to troubleshoot the problem!

You can easily test the electronic EGR valve on your 3.1L Buick Regal or 3.1L Oldsmobile Cutlass Supreme without expensive diagnostic equipment.

In this tutorial, I'll explain how to step by step. You'll quickly determine if the EGR valve is good or bad with your test results.

You can find this tutorial in Spanish here: Cómo Probar La Válvula EGR (1990-1993 3.1L Buick Regal, Oldsmobile Cutlass Supreme) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 3.1L Buick Regal: 1990, 1991, 1992, 1993.
• 3.1L Oldsmobile Cutlass Supreme: 1990, 1991, 1992, 1993.

Important Testing Tips

Although testing the EGR valve isn't a complicated process, please keep the following precautions in mind:

TIP 1: You'll need to remove the EGR valve from the vehicle to test it with the instructions in this tutorial.

It's important to remove the EGR valve with a cold engine. If the engine has been running for any length of time, let it cool down completely.

The EGR valve can get very hot if the engine has been running for any length of time.

TIP 2: You'll need to use jumper wires with insulated alligator clips to bench-test the EGR valve using this tutorial's instructions. The insulated alligator clip jumper wires will help you avoid short-circuit complications.

TIP 3: You'll need a 9 Volt alkaline battery to test the EGR valve solenoids. Although you can use the vehicle's battery, it's easier and safer to use a 9 Volt battery.

Symptoms Of A Bad EGR Valve

An EGR system failure will usually cause an engine performance problem but not always.

Certain types of EGR failures don't cause symptoms except to illuminate the check engine light and set an EGR system diagnostic trouble code (in the fuel injection computer's memory).

Whether the EGR system failure causes an engine performance issue or not, the EGR system failure will set the following OBD I EGR valve diagnostic trouble code:

• Code 32: EGR System Error.

You'll also see one or more of the following symptoms:

• Rough idle.
• Really bad gas mileage.
• Lack of power as you accelerate the vehicle down the road.
• Vehicle seems to run OK above 30 miles and hour but once you come to an idle, the engine barely stays running.
• Vehicle runs great, just the annoying check engine light is on with diagnostic trouble code 32 stored in the fuel injection computer's memory.

EGR Valve Circuit Descriptions

The EGR valve connector has five wires sticking out of it. To successfully diagnose the EGR valve, we need to know what each one does.

The following table has a brief description of each:

Wire	Color	Description
A	Light Blue (LT BLU)	Solenoid A Control
B	Brown With White Stripe (BRN/WHT) or Brown (BRN)	Solenoid B Control
C	Red (RED)	Solenoid C Control
D	Brown (BRN)	12 Volts

Tools Needed To Test The EGR Valve

You won't need expensive diagnostic equipment to test the EGR valve, just a few basic things.

Here's a list of the basic tools you'll need to use the information in this tutorial

• Jumper wires with insulated alligator clips on the ends.
• A 9 Volt alkaline battery.
• A multimeter.

You can buy the insulated alligator clip jumper wires at your local auto parts store or you can buy them online here:

TEST 1: Making Sure The EGR Valve Is Getting 12 Volts

The EGR valve is made up of three solenoids. All three need 12 Volts to function.

So for our first test, we're going to make sure that the EGR valve is getting 10 to 12 Volts.

The wire that delivers this voltage is the brown (BRN) wire that connects to the female terminal labeled with the letter D in the photo above.

These are the test steps:

1. 1

   Disconnect the EGR valve from its connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

   Connect the black multimeter test lead to the battery negative (-) terminal.

4. 4

   Turn the key to the ON position but don't crank or start the engine.

5. 5

   With the red multimeter test lead, gently probe the female terminal labeled with the letter D.

6. 6

   Your multimeter should read 10 to 12 Volts DC.

Let's interpret your test result:

CASE 1: The multimeter registered 10 to 12 Volts. This is the correct and expected test result.

Now that you've confirmed that the EGR valve is getting power, the next step is to check the internal resistance of each solenoid. For this test, go to: TEST 2: Testing The Resistance Of The Solenoids.

CASE 2: The multimeter did not register 10 to 12 Volts. Without power, the EGR valve will not function.

Your next step is to find out why this voltage is missing and resolve the issue. Once power is restored, repeat this test.