2003 Mercury Grand Marquis OBD2 Code P0228 Throttle/Pedal Position Sensor/Switch C Circuit High Input

P0228 code definition

Throttle/Pedal Position Sensor/Switch C Circuit High Input

What the P0228 code means

P0228 is a generic OBD-II code which indicates that the throttle/pedal position sensor/switch C circuit has a high input problem causing the sensor input to the engine control module (ECM) to be higher than the expected voltage input compared to the redundant throttle position sensor A, or above specified range.

What causes the P0228 code?

• The ECM detects that the sensor circuit voltage is above the specified range for the sensor

• Short 5 volt reference to the signal wire could cause low voltage to the ECM. This can be from external wiring problems, or from an internally shorted sensor

What are the symptoms of the P0228 code?

• The Check Engine Light and Electronic Throttle Control (ETC) Light will be illuminated

• The ECM goes into failure limp home mode; drive complaints may vary depending on manufacturer programming

• The throttle is shut completely during stops to prevent excessive RPM's

• The throttle sets to a fixed position during acceleration to limit throttle opening

• Uneven idle or jerking during braking, due to the closed throttle position

• Limited acceleration due to very poor throttle response, or no response at all, during acceleration

• Vehicle speed limited to 32 mph or less

• Disabled cruise control

How does a mechanic diagnose the P0228 code?

• Scans codes and documents the freeze frame data in order to verify the problem

• Clears the engine and ETC codes to verify whether the concern comes back

• Does a visual check of the wiring and connections to the throttle body sensors for shorting or burned wires, which could cause a short to power

• Checks scan data to see if sensor signal voltage is shorted to power, and follows pinpoint testing steps to find the short circuit

• Disconnects and checks the sensor resistance to see if sensor short is internal

Common mistakes when diagnosing the P0228 code

Follow these simple guidelines to prevent misdiagnosis:

• Do a visual check of the wiring to the sensor to make sure they are not shorted in any way

• Look for any problems with burnt or cut wiring to the sensor, or corrosion in the connections

How serious is the P0228 code?

• Any problems with the throttle sensor cause the limp mode to be activated

• The engine will go into limp home mode and systems will be limited, depending on the manufacturer

• The 2003 Mercury Grand Marquis speed will be limited to less than 35 mph

• The engine will lack acceleration or have limited acceleration

• The engine idle will be low and erratic when coming to a stop

What repairs can fix the P0228 code?

• Repairing or replacing shorted wiring to the sensor
• Replacing a defective throttle body control assembly if it is internally shorted
• Replacing or reprogramming the ECM if so directed by the pinpoint tests

Additional comments for consideration regarding the P0228 code

The code P0228 is triggered when the signal getting to the ECM is higher than specified, and can be due to a short in the wire harness between the sensor and the ECM. This code is not used by most manufacturers and approved pinpoint tests should be followed.

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