NEXON DIAGNOSTIC MANUAL

OSPREY- Application

DTC Troubleshooting Data

Version: 4.0

Date: 10-02-2017

Prepared by: Mithipati Prasad

Checked by: G S Raju / Senthilnathan S

Page: 155 of 654

TATA MOTORS Ltd.

This document must not be used in any way, such as copying and redistributing to third parties, without the consent of author.

P0194: Rail Pressure Fault Signal – Pressure drop

Overview:

DTC Description as per ISO standard

Fuel Rail Pressure Sensor “A” Circuit Intermittent/Erratic

ECU Pin Number

Customer Symptom

Once the engine is started and running - Engine vibrates and makes

noise,

Power loss

Engine will stop after delay.

Fault Effects (On Vehicle)

Group Fault for Engine stop after delay gets activated.

Group Fault for disabling pilot injection will get activated

Rail Valve Discharge will be disabled, EGR will be disabled,

Allows the IMV to operate without trim values, Deactivates the Leak

Detection test, Forces the IMV to open fully,

Limits the System Pressure demand to calibratable pressure in bar,

Deactivates the Rail pressure sensing/ Measurement,

Rail Pressure Build measurement is deactivated,

Disables the Rail pressure control fault detection

Limp Home Mode activated.

Lamp Status (If Any)

CE & MIL Lamp is on.

Fault Detection Condition (Root cause)

This DTC gets logged due to drop in rail pressure. If rate of change (in

decrement) of rail pressure is greater than a calibratable threshold

Normal Operating Condition

No faults related to Rail Pressure circuit.

Probable Trouble Area

Rail pressure sensor, ECU, Wiring harness

Healing Condition

Clear the errors, Ignition OFF to ON, engine idle, fly-up and specially

vehicle running in different speed condition

Component Details:

Rail pressure sensor is a piezoelectric type one, which is used to measure the fuel pressure inside the Rail. It provides the

pressure in terms of voltage to the ECU. This rail possesses an under pressure supply of diesel fuel which is ready to be

used by the injectors. The drop of pressure in the rail is immediately signaled by the sensor to the engine control unit. This

is followed by the restoration of pressure in the pump. It is the engine control unit that controls the fuel supply of the rail

from a pump possessing very high pressure. This is done by using a valve for controlling the pressure of fuel.

Preliminary Checks

Check whether the customer voice / view about the issue is matching with the fault effects mentioned above. If

yes, go ahead with next steps. If not, check for other DTC’s presence.

Check whether similar complaints are earlier reported. If yes, perform the preliminary checks with respect to

earlier issue closure.

Check ECU pins and connector, replace if found defective.

Check HP circuit; refer HP circuit check and rectification procedure.

Check LP circuit; refer LP circuit check and rectification procedure.