Blue Print solutions: erratic running of the Fiat 1.9 JTD engine

15 Jul 2023

The 1.9 diesel engine has been installed under various names in vehicles from Alfa Romeo, Fiat, Opel, Vauxhall, Saab and Suzuki. The experts at Blue Print suggest what could be causing its erratic performance.


  • The engine does not run smoothly.
  • Lack of power.
  • Uneven engine performance at low revs.
  • Low free engine speed.

The above symptoms are accompanied by a lit engine light.
The following fault codes can be read in the engine control unit:

  • P0401 EGR Solenoid valve blocked in closed position.
  • P0402 EGR Solenoid valve blocked in open position.



The cause of these symptoms may be excessive soot deposits causing blockage of the EGR valve.

Remove the EGR valve, check for excessive soot deposits and replace if necessary. After fitting a new EGR valve, check the system for proper operation. After the engine has warmed up to operating temperature, connect a suitable diagnostic tester and check for fault codes.

Then select the Mass Air Flow (MAF) and Exhaust Gas Recirculation (EGR) valve items from the data list. When the engine is running at idle – when the EGR valve is closed – the flow meter reading should be 400-600 mg/sec.

When the power consumers are switched off and the accelerator pedal is depressed several times, the flow meter parameters should change rapidly.
When the engine is running at low revs – when the EGR valve is open – the flow meter reading should be 150-400 mg/s.

More technical information can be found at



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