Check Engine LIght Problem code P1491
Don't rush to replace the fan itself until you have tested it. Check the fan relay and relay fuse inside the vehicle. Hopefully it will be just a failed relay and replacement ($12 at dealer) or/and an inexpensive 10amp or 30amp fuse. There can be multiple issues causing this code.
In my case, the fan relay failed (burnt). 2000 Dodge Durango. The PCM was also damaged and requires replacement, awaiting delivery. A remanufactured PCM can be purchased online for substantial less than at the dealer. We tested the fan by supplying power directly to the fan and it runs fine. We had to remove a cover (easy to remove) under the vehicle near the fan to gain access to the connector Use a fused link for testitng to prevent damage during the test. Using a multimeter, I found power 12.5volts from the 30amp fuse circuit which supplies the power for the fan, 12.5 volts from the PCM circuit with the key on, but only 5.16volts from the 10amp fuse circuit with the key on. A continuity test showed the 10amp fuse inside the fuse box inside the vehicle was good. The 30amp fuse in the power distribution box was good when tested for continuity. Checked resistance on all curcuits and they were well within limits. I also checked the wiring to the fan for continuity and resistance. After my tests were completed, a Dodge technican concluded the PCM is bad and is not grounding the circuit as it should. If you want to troubleshoot this yourself, see if your local library has access to ALLDATA which will have diagnostic information and the diagrams of the circuit involved. A Haynes manual for the vehicle, I purchased one at Autozone, can be helpful also.
on Sep 13, 2014