TEST 6: EGR Solenoid Resistance Test
The EGR valve is exposed to intense heat from the engine and the exhaust gas that flows thru it, which will eventually cause the solenoid to fail.
The EGR valve solenoid will usually experience an internal short-circuit or open-circuit problem.
We can quickly check if this has happened by performing a multimeter resistance test on the solenoid.
If the solenoid has suffered an internal short-circuit problem, you'll see a resistance reading of 0 Ohms.
If the solenoid has suffered an open-circuit problem, you'll see a resistance value in the thousands of Ohms or the letters OL displayed on your multimeter (digital).
IMPORTANT: The EGR valve has to be at ambient temperature to get an accurate test result. If the EGR valve is hot, let it cool down completely.
NOTE: This test is done on the male spade terminals of the EGR valve itself and NOT on the female terminals of its 5-wire connector.
These are the test steps:
- 1
Place your multimeter in Ohms mode.
- 2
Disconnect the EGR valve from its pigtail connector.
- 3
Connect the red multimeter test lead to the male terminal labeled with the letter A.
- 4
Connect the black multimeter test lead to the male terminal labeled with the letter E.
- 5
The multimeter should read 8 to 9 Ohms.
Let's interpret your test results:
CASE 1: The multimeter registered the indicated Ohms value. This is the correct and expected test result.
Your next step is to remove the EGR valve and check for carbon build-up on the EGR valve itself and the EGR valve pipe's inlet. Go to: TEST 7: Checking For Carbon Build Up.
CASE 2: The multimeter registered a resistance value close to 0 Ohms. This test result confirms solenoid has suffered an internal short-circuit problem. Replace the EGR valve.
CASE 3: The multimeter registered a resistance value in the K Ohms range or the letters OL. This test result confirms solenoid has suffered an internal open-circuit problem. Replace the EGR valve.
NOTE: If your multimeter reports a resistance value in the K Ohms range, it means that the resistance is in the thousands of Ohms range.
TEST 7: Checking For Carbon Build Up
As mentioned at the beginning of this tutorial, the EGR valve can become stuck open or closed.
In most cases, the culprit behind this type of EGR valve problem is black soot from the exhaust, which builds up on the EGR valve pintle and causes it to stay open or closed.
This buildup of carbon particles (soot) also clogs the exhaust gas passages that connect the EGR valve to the intake manifold. It doesn't happen overnight, but it will.
To find out if carbon buildup is causing these issues, we'll remove the EGR valve and inspect its pintle and orifices (ports).
We'll also check the EGR ports on the intake manifold to see if they're blocked with carbon buildup.
These are the test steps:
- 1
Remove the EGR valve from its place on the intake manifold.
- 2
Inspect the EGR valve pintle and the EGR orifices.
- 3
Check that the EGR ports on the intake manifold.
Let's interpret your test results:
CASE 1: The EGR valve pintle and all ports ARE NOT blocked with carbon. This is the correct test result.
All of the tests you've performed up to this point have not found any problems with the EGR valve.
CASE 2: The EGR valve pintle and/or EGR ports on the intake manifold are blocked with carbon. Your next step is to remove the carbon deposits.
Once the carbon has been removed, verify the EGR pintle can completely close on its seat.
Reinstall the EGR valve, clear the EGR valve fault codes (that were lighting up the check engine light) and road test the vehicle to see if the problem is solved.
CASE 3: Only the EGR valve pintle was blocked with pieces of carbon preventing it from fully closing. This condition allows exhaust gas to enter the intake manifold at all times, causing a rough idle and/or engine stall problem.
Remove the carbon blocking the EGR valve's pintle. Re-install the EGR valve, clear the EGR valve fault codes (that were lighting up the check engine light), and road test the vehicle to see if the problem is solved.
CASE 4: Only the EGR ports on the intake manifold were blocked with carbon. This blockage will not allow exhaust gas to flow into the intake manifold.
Your next step is to clean/remove the carbon blockage. Once the blockage has been removed, reinstall the EGR valve, clear the EGR valve trouble codes (that were lighting up the check engine light [CEL]), and road test the vehicle to see if the problem is resolved.
If this info saved the day, buy me a beer!
