P0656 Fuel Level Output Circuit Malfunction

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Cost of diagnosing the P0656 code

P0656 is a diagnostic trouble code (DTC) for "Fuel Level Output Circuit Malfunction". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

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P0656 code definition

The P0656 code means that the powertrain control module (PCM) has read an abnormal voltage level from the fuel level output circuit.

What the P0656 code means

The P0656 means that something in the fuel level output circuit's electrical connections or wiring, which run from the PCM to another controller interface module, is malfunctioning. The PCM gathers data from the engine in order to feed the most important information to the other electrical modules. Flawed information coming from one of the output circuits in the PCM can greatly impact the performance of the system.

What causes the P0656 code?

The most common causes for this code are:

  • Defective system circuitry
  • Wiring and/or electrical connectors that are corroded, broken or loose
  • A defective PCM
  • A fault in the low fuel level indicator bulb or fuel level sensor

What are the symptoms of the P0656 code?

The appearance of a P0656 code may come with no symptoms other than the check engine light or a non-operating low fuel indicator. Some vehicles may also experience inaccurate fuel gauges, or even inoperable gauges.

How does a mechanic diagnose the P0656 code?

To diagnose the P0656 code, the mechanic will use an OBD-II scanner. However, it is important to begin with a visual inspection of a PCM, the engine wiring harness, and all ground wires as well as electrical connectors. Replacing and repairing anything that is damaged, disconnected or loose, the mechanic will have to re-run the diagnostic to see if the code returns.

If so, look at the freeze frame data to see where the code appears in the order of codes saved because there may be other fuel level related codes that will make it easier to identify the actual cause of this code.

Common mistakes when diagnosing the P0656 code

The most common mistake made when diagnosing the P0565 code is that the engine's coolant temperature sensor is replaced prior to a more in-depth diagnostic. This allows the PCM driver to be overlooked, and it is this which is most often a cause for this code to appear.

How serious is the P0656 code?

The P0656 code does not interfere with vehicle operations, but it can cause the vehicle to display inaccurate gas levels and to persistently cause the PCM to run inefficiently due to flawed data.

What repairs can fix the P0656 code?

The P0656 is best repaired using the following processes:

  • A technician should verify the code with a scanner, and begin repairing the issue by resetting the codes and doing a road test to determine if the P0656 code returns. If so, they must then move on into a more in-depth diagnosis.
  • The next step is to do a visual inspection on the PCM and the wiring harnesses, ground wires, and connectors. Anything that is frayed, corroded, disconnected or damaged must be replaced and the diagnostics re-run to determine if the code will reappear.
  • If the code returns, it is necessary to examine the system circuitry. This may require the use of an Autohex or Tech II scanner that looks into the CAN bus to detect the problems. Because the most common cause for this code is loose or disconnected wiring, the diagnostic CAN scanners are typically the most effective in finding the issue and making the repair.

Additional comments for consideration regarding the P0656 code

The CAN scanners can provide you with pin values and assess individual control modules without risking any electrical glitches due to flawed testing with a probe. Though individual control modules rarely fail, it is possible, and the CAN scanner may detect this, as well as the control module ground circuits.

Need help with a P0656 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

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JOHNNY

33 years of experience
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JOHNNY
33 years of experience
BMW 325Ci - Check Engine Light is on - Sacramento, California
He was great explained everything to me and have now booked him for another appointment. Thanks johnny.

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41 years of experience
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Ronald
41 years of experience
Mercedes-Benz C300 - Check Engine Light is on - Spring, Texas
Mister Ron was very nice and took time out to explain any concerns I might have about my car. He also made sure he communicated with me when he was on his way, once he was outside, and when we was done working on my car. I appreciate that considering I have a newborn that I had to look after.

Ronald

41 years of experience
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Ronald
41 years of experience
Ram 1500 - Check Engine Light is on - Spring, Texas
Extremely satisfied with the service, he was able to come out and diagnose almost immediately. We purchased the parts, he came back installed them and been running great since. Would definitely recommend him and will not hesitate to call again if needed.

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Dodge Neon - Check Engine Light is on - Tempe, Arizona
I truly enjoy Scott as he has done work for me in the past. Scott is very friendly, knowledgeable, and a true professional! I highly recommend him.


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