Nov 202016

2006 Ford Five HundredI used the OBD II / EOBD CODE READER and found the following code(4 error codes)
P0171 System too lean Bank 1
P0374 Timing Reference Hig n Resolution Signal A No Pulses
P0171 System too lean Bank 1
P0374 Timing Reference Hig n Resolution Signal A No Pulses
The same code reader gave me RPM(rpm): 705.50 while the engine was running but the gear was in Parked position

I don’t feel anything while driving the 2006 Ford Five hundred SEL (I don’t have much knowledge about vehicles). It accelerates well and goes easily to 40miles per hour when given the acceleration (I have not tried beyond 40 miles/hr in order to avoid any damage, as I bought it recently and want to repair it before use). The odometer reads about 200,000 miles.  I showed to a local mechanic he said the gear is either in 2nd or 3rd (limp mode) after a short test drive, which made me little worried, what can be the possible reasons of this errors and what should I do to make it a smooth running vehicle?


Not sure if you made an error yourself when posting the codes but you show only 2 codes and posted them twice. None of the codes indicate anything to do with the transmission. There shouldn’t be any correlation between the two codes. So, look at them separately. As for code p0374 the Optical sensors are the camshaft and crankshaft sensors.

Ford Code P0171 – Fuel Injection System Too Lean Bank 1

Code P0171 Possible causes

– Intake air leaks
– Faulty front heated oxygen sensor
– Ignition misfiring
– Faulty fuel injectors
– Exhaust gas leaks
– Incorrect fuel pressure
– Lack of fuel
– Faulty Mass Air Flow (MAF) sensor
– Incorrect Positive Crankcase Ventilation (PCV) hose connection

Code P0374 – Timing Reference High Resolution Signal ‘A’ No Pulses

 Code P0374 Description

The optical sensor provides a high resolution signal to the Powertrain Control Module (PCM) by counting pulses on the sensor disk located in the injection pump. The high resolution is one of the most important inputs by the PCM for fuel control and timing. This test monitors the number of high resolution pulses which have been missed (not detected). It’s based on a comparison between the number of pulses that were detected since the last pump cam pulse and the number of the pulses that should have occurred. There are approximately 64 high resolution pulses for every cam pulse.

Code P0374 Possible causes

– Timing Reference Optical Sensor harness is open or shorted
– Timing Reference Optical Sensor circuit poor electrical connection
– Faulty Timing Reference Optical Sensor
– Damaged Powertrain Control Module (PCM)
Sensor Location Diagram

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