P1391 Daihatsu U4 DTC Code

Daihatsu U4 Engine Specifications:

Engine Type :	Multi-Cylinder Engine
Cylinder Type :	V-Type Engine
Engine Air Intake Process :	Turbocharged Engine

Your Daihatsu U4 engine control system detects a problem, the computer stores the diagnostic trouble code P1391 in its memory. To figure out what is wrong with your vehicle you must first extract the P1391 DTC For Daihatsu U4.

A good ground connection is also extremely important. P1391 Daihatsu U4 engine problem because the presence of voltage at the panel harness won't make the panel work if there is a bad ground connection. Since the instrument cluster is mounted in a plastic dash, a separate ground wire or ground circuit through the wiring harness is usually needed to complete the power circuit. Refer again to the wiring diagram to find the ground path, and then check it with your ohmmeter. Do not use a self-powered test light because it cannot measure resistance (any resistance will lower circuit voltage).

P1391 Daihatsu U4 DTC Meaning

P	Powertrain Code - Problem is related engine, transmission and emissions systems.
1	MFG - Manufacturer Specific
3	IC Module 4X Ref Circuit Intermittent, No Pulses
9	TP Sensor Learn Not Complete
1	PCM Stack Overrun

The original multi-displacement system turned off opposite pairs of cylinders, allowing the engine to have three different configurations and displacements. P1391 Daihatsu U4 code had an elaborate diagnostics procedure, including showing engine trouble codes on the air conditionning display. However, the system was troublesome, misunderstood by customers, and a rash of unpredictable failures led to the technology being quickly retired.