P2066 Fuel Level Sensor B Circuit Range/Performance
OBD-II Trouble Code Technical Description
Fuel Level Sensor "B" Circuit Range/Performance
What does that mean?
This generic powertrain/engine diagnostic trouble code typically applies to all OBDII equipped engines, but shows up more often in certain Chrysler, GM, Ford, Lincoln, Mercury, Kia, Mazda, Mercedes Benz, Infiniti, Nissan and Subaru vehicles.
The Fuel Level Sensor (FLS) is usually found mounted in the fuel tank, usually in the top of the fuel tank / fuel pump module. The FLS converts the mechanical fuel level into an electrical signal for the Powertrain Control Module (PCM). Typically, the PCM will then inform other controllers utilizing the vehicle’s data communication bus.
The PCM receives this voltage signal to determine how much fuel it has in the fuel tank, monitoring fuel usage and thereby determining fuel economy. This code is set if this input does not match normal operating voltages stored in the PCM’s memory, even for a second, as this diagnostic trouble code demonstrates. It also looks at the voltage signal from the FLS sensor to determine if it is correct at initial Key On.
P2066 could have been set because of mechanical (incorrect fuel level rationality; refueling the vehicle with the ignition switch "on" or even engine running can do this. Fuel level changes too rapidly which is not normal) or electrical (FLS sensor circuit) issues. These cannot be overlooked in the troubleshooting stage, especially when dealing with an intermittent problem.
Troubleshooting steps may vary depending upon manufacturer, type of FLS sensor and wire colors. Refer to a vehicle specific repair manual to determine the location of the "B" circuit.
Related fuel level sensor B circuit trouble codes include:
P2065 Fuel Level Sensor "B" Circuit Malfunction P2067 Fuel Level Sensor "B" Circuit Low Input P2068 Fuel Level Sensor "B" Circuit High Input P2069 Fuel Level Sensor "B" Circuit IntermittentSeverity & Symptoms
Severity depends upon the failure. If a mechanical failure; severe. If an electrical failure, not as severe, as the PCM can compensate for it. The compensation usually means that the fuel gauge reads Empty or Full all the time.
Symptoms of a P2066 engine code may include:
Malfunction Indicator Lamp (MIL) illuminated Decrease in perceived fuel economy Decrease in Distance to Empty mileage Incorrect fuel level on gauge in instrument cluster – always reads wrongPotential Causes
Typically the causes for this code to set are:
Open in the signal circuit to the FLS sensor - possible Short to voltage in the signal circuit to the FLS sensor- possible Short to ground in the signal circuit to the FLS sensor- possible Failed FLS Sensor / sensing arm stuck mechanically - likely Failed PCM - unlikelyDiagnostic and Repair Procedures
A good starting point is always a technical service bulletin (TSB) search for your particular vehicle. The vehicle manufacturer may have a PCM flash/reprogram to cover this issue, and it pays to check on this before you find you’ve gone down a long/wrong path.
A good example of this is on Ford products where an aftermarket remote start system has been installed. It can cause a false code to be set. There is a TSB covering this subject and should be followed in order to properly diagnose this condition. Auxiliary fuel tanks are covered in this TSB as well. Gravity feed tanks are not recommended for use on these systems and when refueling Ford trucks. It is recommended to refuel the main tanks with the ignition switch in the off position.
Next, locate the Fuel Level Sensor (FLS) on your particular vehicle. This sensor is usually found mounted in the fuel tank or possibly even in the top of the fuel tank / fuel pump
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