Q: car cranks but wont start. check engine light on. code p0685

asked by on October 04, 2016

Drove home from work, stopped on my way. car would crank but not start. my dash said "engine power reduced" i unhooked the battery and came back to the car an hour or so later and it started right up, I drove it about 3 miles and same thing, except this time it happened while i was driving. I called a tow truck driver and when he got there he jump started the car and it started right up on the first try. "Engine power reduced" warning went away but check engine light came on. I bought a code reader and it gave me p0685 "Ecn/pcm power control module relay/open". Car starts anytime i try to start it now, but i dont want to drive it anywhere and have to get it towed home again.

My car has 149000 miles.
My car has an automatic transmission.

Ignition Relay Replacement $104.03 - $231.75 Get a Quote

The code P0685 indicates a problem with Engine Control Ignition Relay Control Circuit. This may have a poor connection or need to be replaced. I would recommend having an expert from YourMechanic come to your home to diagnose and repair.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Oil leak above oil pan - 1985 Ford LTD Crown Victoria
Simply tightening this plug, whether it's the oil pan drain plug, or another high pressure oil plug of some sort, may only stop the leak temporarily at best. It could also strip the threads. There will likely be a fiber,...
Engine trouble
Hi Jo: Unfortunately, we need more specific information about your vehicle in order to recommend a service or to guess as to what's going on with your vehicle. If the engine is low on oil (https://www.yourmechanic.com/services/oil-level-is-low-inspection) it tends to make...
The Check Engine Light is on
Hi there. There are a lot of things that can cause the Check Engine Light to be illuminated. A flashing check engine light is a sign of serious trouble. If the light is not flashing, then I would use a...
P0008 error code is shown
The P0008 code (https://www.yourmechanic.com/article/p0008-obd-ii-trouble-code-engine-positions-system-performance-bank-1-by-paul-lancette) you are receiving is telling you the camshafts and the crankshaft are reading that they are out of sync. The computer will run tests on the alignment of the camshafts to each other, and with the...
Squeking in my front end while driving and turning the wheels
The noise is coming from the sway bar links, tie rod ends or lower ball joints. You will need to try and duplicate the noise without driving the vehicle and when noise is heard just put you hand on the...
Dead truck battery every time it's left off for a few hours.
If the battery is new and charging system output has been measured and is within specifications, the only reason a battery will discharge is if the car sits for a long period of time (batteries will self-discharge even if not...
My Porsche Cayenne is shutting down in traffic and cutting off when I start the vehicle
When your car stalled, most likely it set one or more trouble codes in the engine ECU. Those codes can be read by a technician equipped with a Porsche appropriate scan tool. You might be able to see the problem...
I have a 05 Chrysler 300 with a check engine light on indicating tcc solenoid is out of range. What does this mean?
Hi there. This article would be a good one for you to read (https://www.yourmechanic.com/article/p2761-obd-ii-trouble-code-torque-converter-clutch-pressure-control-solenoid-control-circuit-open-by-elan-mcafee), as it will outline what the P2761 OBD-II code means, what causes the TCC solenoid problem and possible repair solutions.
When I get a jumpstart it works drive it for 10 miles and cut it off and it want crank again it's completely dead
You possibly have a dead battery and/or a faulty charging system. The very first thing to do is be sure you have a fully, 100% charged battery that passes a load test (https://www.yourmechanic.com/services/battery-is-dead-inspection). If the battery passes a load test...

Related articles

Symptoms of a Bad or Failing Ignition Switch
If your car cannot start, starts but quickly dies, or has electrical components that stopped working, you may have to replace the ignition switch.
Symptoms of a Bad or Failing Ignition Lock Assembly
If your key is stuck in the ignition, won't go in, or can't start the car, you may need to replace the ignition lock assembly.
How Long Does an Ignition Relay Last?
When When trying to crank a car, you will need a few vital components to be working in order for the process to be successful. On most cars, there is an intricate network of relays and switches that allow for...