This step-by-step guide will show you how to test the internal resistance of the fuel injectors using just a multimeter.
It's a simple test that checks if the injector is electrically sound —no special tools or scan tool needed.
You'll learn how to spot a shorted or open injector and compare resistance values across all eight cylinders.
I'll also show you what those Ohm readings mean and what to do if one injector's reading is way off.
This test is a great starting point when you're tracking down a hard-to-find misfire or rough idle issue.
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- 4.7L V8 Dodge Dakota: 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009.
- 4.7L V8 Dodge Durango: 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009.
CYLINDER MISFIRE DIAGNOSTICS:
INJECTOR SPRAY TESTS:
Symptoms Of A Bad Fuel Injector
When a fuel injector fails on your 4.7L Dodge Dakota or Durango, it can disrupt engine performance by causing a lean condition in one or more cylinders —leading to rough idle, hesitation, or a misfire.
The three most common ways that a fuel injector can fail are:
- Internal electrical failure: The fuel injector burns out internally and stops spraying fuel altogether.
- Clogged nozzle or pintle: Fuel flow is restricted, leading to a weak or uneven spray pattern.
- No injector pulse: The injector doesn't fire because it's missing power or its switching signal from the PCM.
No matter what the root cause, a bad fuel injector will cause the engine to idle rough and miss when you accelerate it down the road.
Since each injector is responsible for delivering fuel to one cylinder, even a single bad one can cause noticeable problems.
Here are the most common symptoms of a failing or dead injector:
- Rough idle: The engine shakes or feels unstable at stop lights or in Park.
- Engine misfire: You'll feel hesitation or a stumble during acceleration.
- Check engine light (CEL): A bad injector can trigger injector or misfire codes like:
- P0201 to P0208 —These indicate a specific injector circuit malfunction (one code per cylinder).
- P0301 to P0308 —These are cylinder-specific misfire codes that may point to a weak or non-functioning injector.
- Bad gas mileage: The PCM may try to compensate with extra fuel, wasting gas.
- Hard starts or extended crank time: A leaky or stuck-open injector can flood the engine with fuel.
If you're seeing one or more of these symptoms —especially combined with misfire or injector codes— it's time to test the injectors and see if one has failed.
Where To Buy The Fuel Injectors And Save
You can the fuel injectors at your local auto parts store, or you could buy them online and save a few bucks.
Disclosure: As an Amazon Associate, I earn from qualifying purchases. Buying through these links helps support this site at no extra cost to you. I truly appreciate it!
Understanding Fuel Injector Testing Strategy
Before we get started with the actual multimeter resistance test, I want to let you know that troubleshooting a bad fuel injector involves more than just checking resistance.
In fact, resistance testing is only one half of a complete fuel injector diagnostic strategy —and both parts are important when you're chasing down a stubborn misfire.
The resistance test checks for internal electrical problems —like a short (0 Ohms) or an open-circuit (OL or thousands of Ohms). These issues will keep the injector from working at all and are easy to catch with a multimeter.
But injectors are electro-mechanical valves —the internal windings may test OK (good resistance), yet the pintle or nozzle can still be clogged or stuck shut. I've seen this many times in my misfire diagnostic work.
This is where the fuel injector spray pattern test comes in —it's the second half of the strategy. Once you've identified the misfiring cylinder and confirmed its injector passed the resistance test, removing it and checking its spray pattern is the best next move.
You can learn how to do this step-by-step with the following tutorial:
Alright, now that you know the full strategy, let's kick things off by testing the injector's resistance with a multimeter.
How To Test Fuel Injector Resistance With A Multimeter
This resistance test will help you figure out if one of your fuel injectors has failed internally —either from a short-circuit or an open-circuit. The test is easy to do and works whether you're checking all eight injectors or just one (for example, if you've already pinpointed a misfiring cylinder).
The fuel injectors on your 2000–2007 4.7L V8 should measure between 10.8 to 13.2 Ohms when cold. Readings outside that range usually point to a problem, for example:
- If you see around 0 Ohms, the injector has an internal short and is fried.
- If you see something in the thousands of Ohms —or your meter reads infinite resistance— the injector is open and no longer functioning.
Be sure to run this test on a cold engine —whatever your current ambient temperature is. If the engine has been running, give it plenty of time to cool before getting started.
And while you're at it, take a good look at the injector connectors. These are known for broken locking tabs, which can lead to poor connections and intermittent problems down the road.
If you don't have a multimeter or need to upgrade your, I've included a trusted model below that I personally recommend and have used for years. It's accurate, reliable, and perfect for this kind of diagnostic work.
- Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (Amazon affiliate link).
Alright, here are the steps:
- 1
Disconnect the fuel injector's connector.
Start with the one you suspect is causing the problem, then compare it against at least two known-good ones.
You can test all eight if you'd like —same steps apply to each one. - 2
Set your multimeter to Ohms (Ω) mode.
- 3
Touch the multimeter probes to the injector's two terminals.
Don't worry about polarity —resistance tests aren't sensitive to which lead goes where. - 4
Check the reading. You're looking for something between 10.8 and 13.2 Ohms.
- 5
Repeat the test on the remaining injectors, especially if you suspect more than one might be failing.
Let's look at what your test results mean:
CASE 1: All tested injectors fall within spec (10.8–13.2 Ohms). This tells you the internal windings are good and the injector isn't shorted or open.
But don't rule it out yet —an injector can still be clogged and not spraying fuel properly. If misfire symptoms are still present, the next step is to check the spray pattern and fuel delivery:
Also, be sure to review this core misfire diagnostic guide:
CASE 2: One or more injectors showed a resistance way outside the 10.8–13.2 Ohm range. That's a clear sign the injector has failed internally and needs to be replaced.
If you're ready to replace it, I've included a trusted option below —it's from a trusted automotive brand I personally recommend and have used many times:
Using these links helps support the site and keeps tutorials like this free. I only recommend parts from automotive brands I've used and trust —and it won't cost you anything extra. Thanks for your support!
More 4.7L V8 Dodge Dakota And Durango Tutorials
You can find a complete list of 4.7L Dodge Dakota and Durango diagnostic "how to" tutorials in this index:
Here's a small sample of what's waiting for you there:
- How To Test The Throttle Position Sensor (2000-2007 4.7L V8 Dodge Dakota And Durango).
- How Often Should I Replace The Spark Plugs? (2000-2009 4.7L V8 Dodge Dakota And Durango).
- How To Test The Alternator (2001-2002 4.7L V8 Dodge Dakota And Durango).
- How To Test The Fuel Pump (2000-2007 4.7L V8 Dodge Dakota And Durango).
If this info saved the day, buy me a beer!
