You can easily and quickly test the electronic EGR valve with a multimeter. In this tutorial, I'll explain the tests you need to do step-by-step.
With your test results, you'll easily and quickly find out if the EGR valve is good or bad.
Contents of this tutorial:
- Symptoms Of A Bad EGR Valve.
- EGR Valve Connector Circuits.
- Where To Buy The EGR Valve And Save.
- TEST 1: EGR Pintle Position Signal Test.
- TEST 2: EGR Pintle Position Sensor Performance Test.
- TEST 3: Making Sure The EGR Valve Pintle Position Sensor Is Receiving 5 Volts.
- TEST 4: Making Sure The EGR Valve Pintle Position Sensor Is Receiving Ground.
- TEST 5: Making Sure The EGR Solenoid Is Getting 12 Volts.
- TEST 6: EGR Solenoid Resistance Test.
- TEST 7: Checking For Carbon Build Up.
You can find this tutorial in Spanish here: Cómo Probar La Válvula EGR (1996-2001 4.3L Chevrolet S10 Pickup, GMC Sonoma) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 4.3L Chevrolet S10 Pickup: 1996, 1997, 1998, 1999, 2000, 2001.
- 4.3L GMC Sonoma: 1996, 1997, 1998, 1999, 2000, 2001.
- 4.3L Isuzu Hombre: 1998, 1999, 2000.
Symptoms Of A Bad EGR Valve
For the most part, EGR valve failures usually fall into one of the following categories:
- The EGR valve is stuck open.
- The EGR valve is stuck closed
Usually, if the EGR valve is stuck closed, your vehicle will not experience any engine performance problems, although it will be polluting more and the check engine light will be on.
In most cases where the EGR valve is stuck open, a build up of soot particles and carbon deposits is the cause of the problem.
When the EGR valve is stuck open, you'll usually see engine performance issues such as reduced horsepower, reduced acceleration, reduced fuel efficiency and increased vehicle emissions.
The symptoms a bad EGR valve can cause can vary, but the most common are:
- Check engine light illuminated by one of the following diagnostic trouble codes:
- P0401 EGR System Flow Insufficient.
- P1406 EGR Valve Pintle Position.
- 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 one of the above diagnostic trouble codes stored in the PCM's memory.
- Engine starts and immediately dies.
EGR Valve Connector Circuits
The EGR valve's connector has five wires. Each one has a specific job to do and and the table below provides a brief description of each one:
| Wire | Color | Description |
|---|---|---|
| A | Grey (GRY) | Chassis Ground |
| B | Black (BLK) | Sensor Ground |
| C | Brown (BRN) | EGR Pintle Position Signal |
| D | Grey (GRY) | 5 Volts |
| E | Pink (PNK) | EGR Valve Control |
Where To Buy The EGR Valve And Save
Not sure if the above linear EGR valve fits your particular vehicle? Don't worry. Once you get to the site they'll make sure it fits by asking you the specifics of your particular vehicle. If it doesn't fit, they'll find you the right one.
TEST 1: EGR Pintle Position Signal Test
The EGR valve has a pintle position sensor that reports its pintle position to the fuel injection computer.
The pintle position sensor generates a variable voltage signal that corresponds to the pintle position of the EGR valve.
To start our EGR valve diagnostic, we'll look at what the pintle position sensor reports with the key in the ON position but with the engine off.
The value we want to see is a voltage reading between 0.6 to 0.9 Volts DC, which would indicate the EGR valve pintle is in its closed position.
IMPORTANT: To perform this test, the EGR valve must remain connected to its pigtail connector. To access the signal within the wire, you'll need to back probe the connector or use a wiring piercing probe on the wire. You can see an example of this tool here: Wire Piercing Probe.
These are the test steps:
- 1
Place your multimeter in Volts DC mode.
- 2
Connect the red multimeter test lead to the brown (BRN) wire.
The BRN wire connects to the terminal with the letter C.
NOTE: The EGR valve must remain connected to its pigtail connector to read the pintle position voltage signal. - 3
Connect the black multimeter test lead to battery negative (-) terminal.
- 4
Turn the key to the ON position but don't crank or start the engine.
- 5
Your multimeter should display a voltage reading between 0.6 to 0.9 Volts DC.
Let's interpret your test results:
CASE 1: The multimeter registered 0.6 to 0.9 Volts DC. This is the correct and expected test result and it tells you that the EGR valve pintle is in the correct position (not stuck open).
Your next step is to go to: TEST 2: EGR Pintle Position Sensor Performance Test.
CASE 2: The multimeter displayed a DC voltage above 0.9 Volts. This test result usually indicates the pintle is stuck open.
To investigate this further, go to: TEST 7: Checking For Carbon Build Up.
CASE 3: The multimeter DID NOT display any voltage or a very low voltage. This test result usually indicates that the EGR valve is bad.
To investigate this further, your next step is check the EGR valve pintle position sensor's performance. For this test go to: TEST 2: EGR Pintle Position Sensor Performance Test.
