In this tutorial I'll explain how to test the fuel injectors on the 2.4L equipped Chevrolet Cobalt, HHR, Malibu and the 2.4L equipped Pontiac G5, G6, and Solstice.
The fuel injector test I'm gonna' show you is a simple multimeter resistance test that will let you know if the fuel injector is fried internally (or not).
I'm also gonna' suggest a specific set of troubleshooting tests that'll help you find out if you have a clogged fuel injector on your hands.
Contents of this tutorial at a glance:
NOTE: This tutorial applies to the following 2.4L equipped GM vehicles (since they use the exact same fuel injectors):
- 2.4L Chevrolet Cobalt: 2008.
- 2.4L Chevrolet HHR: 2008.
- 2.4L Chevrolet Malibu: 2008, 2009, 2010, 2012.
- 2.4L Pontiac G5: 2008.
- 2.4L Pontiac G6: 2008, 2009, 2010.
- 2.4L Pontiac Solstice: 2008, 2009.
NOTE: The following fuel injector circuit diagrams may be of help:
- Fuel Injector Circuit Wiring Diagram (2008-2009 2.4L Chevrolet Malibu And Pontiac G6).
- Fuel Injector Circuit Wiring Diagram (2008 2.4L Chevrolet Cobalt And Pontiac G5).
Symptoms Of A Bad Fuel Injector
There are two types of fuel injector failures. Either the fuel injector stops injecting fuel completely or it doesn't inject enough fuel.
When a fuel injector stops injecting fuel completely, it's usually due to a short-circuit problem with the fuel injector's internal coil winding.
In these cases, when the injector's internal coil winding shorts out, the fuel injection computer will set a fuel injector trouble code:
- P0201: Injector 1 Control Circuit.
- P0202: Injector 2 Control Circuit.
- P0203: Injector 3 Control Circuit.
- P0204: Injector 4 Control Circuit.
Now, even though the fuel injection computer is able to set a fuel injector trouble code, it usually doesn't. In most cases when a fuel injector is not injecting fuel, the fuel injection computer will set a misfire trouble code:
- P0300: Random Cylinder Misfire.
- P0301: Cylinder #1 Misfire.
- P0302: Cylinder #2 Misfire.
- P0303: Cylinder #3 Misfire.
- P0304: Cylinder #4 Misfire.
Besides a misfire trouble code you're also gonna' see one or more of the following symptoms:
- Rough idle.
- Bad gas mileage.
- A heavier than usual exhaust gas smell coming out of the tailpipe.
- Lack of power when accelerating the vehicle under load.
Testing The Fuel Injector Resistance
The resistance test we're about to do will let us know if the internal coil winding of the fuel injector has suffered a short-circuit problem.
To be a bit more specific, we're gonna' make sure that the resistance value of the fuel injector isn't less than 5 Ohms since this would indicate an internal short-circuit problem.
Also, if the fuel injector resistance is in the K Ohm range (thousand Ohm range), then you can conclude that the fuel injector has suffered an open-circuit problem and is defective.
Although this test does not test for a clogged fuel injector, it's still a good first step in that direction.
These are the test steps:
Place your multimeter in Ohms mode.
Disconnect the cylinder #1 fuel injector from its electrical connector.
Probe male spade terminals of the fuel injector with the multimeter test leads.
Your multimeter should register 11 to 14 Ohms.
Repeat steps 2 thru' 4 on the remaining fuel injectors.
Let's examine your resistance test results:
CASE 1: The resistance of all 4 fuel injectors is within specification. This is the correct test result and it lets you know that the internal coil winding of each fuel injector is OK.
Now, if you suspect that you've got a clogged fuel injector causing a misfire then take a look at the following section: How To Find The Bad Or Clogged Fuel Injector.
CASE 2: One or more fuel injectors' resistance value is not within specification. If the resistance shows that the fuel injector has an open-circuit or short-circuit problem, then you can conclude that it's defective and needs to be replaced.