U1990 Renault Zo Diagnostic Trouble Code

U1990 Renault Zo code definition:
U1990 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Renault Zo.

U1990 Renault Zo is described as Oxygen Sensor Circuit No Activity Detected Bank 2 Sensor 1. This code appears when the PCM (powertrain control module, also known as ECM or engine control module in other brands) remains at or close the 0.450 set voltage point. If the car doesn't start, they will proceed by testing the voltage at the fuel pump connector and see if the fuel pump relay, fuse, and PCM circuitry should be inspected.

Symptoms

Symptoms of a U1990 Renault Zo diagnostic trouble code may include:
  • Engine surge
  • Blown fuse (if applicable)
  • Lack of power
  • Cherry red hot catalytic converter
Place of U1990 in engine

Possible Causes :

  • Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
  • Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
  • A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.

Common Misdiagnoses

  1. Vehicle Speed Output Circuit Problem
  2. Cruise Control Servo Indicates Low Problem
  3. A/C System High Pressure High Temperature Problem
  4. PCM Stack Overrun Problem
  5. Transmission Control Module Reprogrammable Memory Problem

Repair Processes :

Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem. Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed.

Process Tips

Diagnostic trouble code U1990 Renault Zo is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before U1990 Renault Zo.

Fortunately, U1990 Renault Zo is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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