99 Dodge Durango PO206 and PO306: White Smoke, Gasoline Odor, Injector Circuit Issue

Any ideas? Use a noid light to check if the cylinder 6 fuel injector is receiving pulses. If it's pulsing, try swapping the injector with one from another cylinder—this will help determine if the injector itself is faulty. If the code changes, then the injector is defective. If not, the issue lies in the wiring or a faulty throttle position sensor (TPS).

How difficult is it to replace the fuel injector wiring harness? Is there a common location for these connections on a 1999 Dodge Durango?

Why swap parts without testing first? You should test the injector pulse and circuit integrity before replacing components. A noid light or multimeter can quickly identify whether the issue is electrical or mechanical. Swapping injectors may introduce more problems than it solves—especially if you don’t have experience with diagnostics. Have you tested the injector pulse yet?

The fuel injectors for cylinders 6 and 8 were loose, so I replaced both. After replacement, the misfire code disappeared.

And have the codes cleared? Does the truck run smoothly now?

No—the misfire code is gone, but PO206 (injector circuit open for cylinder 6) remains. White smoke and gasoline odor are still present.

Could a cracked head gasket be causing the PO206 code? Many people suggest this, but I don’t smell antifreeze or see coolant in the exhaust—so it seems less likely. Is there any way to confirm if combustion pressure is leaking?

Which code appeared first—PO206 or PO306? Have you tested compression in cylinder 6? Did you check the injector circuit for continuity? White smoke could be related to a misfire, but it might also indicate an electrical fault. Is the white smoke like condensation burning off (non-antifreeze), or does it smell like antifreeze? First, verify injector pulse using a noid light—follow the advice in earlier posts!

Here's what I found: PO306 shows cylinder 6 misfire. I replaced the spark plug and fuel injector. The injector appears to be running wide open, dumping fuel into the exhaust—explaining both white smoke and strong gasoline odor. How exactly do I test for injector pulse or wiring faults? I’m not very mechanically skilled—I’ve only read about these issues in forums.

Go to a parts store with a loaner tool program and borrow a noid light (available at Harbor Freight for under $20). Unplug the injector on cylinder 6 and connect the noid light. Start the engine—if the light flickers, the PCM is sending pulses. If it stays solid or doesn’t flicker, there’s likely no signal—indicating a wiring issue or faulty injector. If you're not confident in your mechanical skills, consult a professional mechanic. A digital multimeter (DVOM) can then be used to test resistance and circuit continuity. Check the injector's resistance—if open, it's defective.

I tested with a noid light—it stayed on solid, not flickering at all. Now I’ll get a digital multimeter to check the wiring circuit for shorts or continuity.

So the injector isn’t pulsing at all—was it new? That suggests a short in the circuit. Use a wiring diagram and DVOM to trace the path from the PCM to cylinder 6’s injector. Look for any damaged wires, connectors, or grounding issues along that route.