P0091 Arista Passy Diagnostic Trouble Code

P0091 Arista Passy code definition:
P0091 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Arista Passy.

P0091 Arista Passy is described as Fuel System Too Rich, which basically means bank 1's oxygen sensor has detected a rich condition of fuel. This means there's not enough oxygen in the exhaust from too much fuel being delivered into the air and gas mixture for combusion. There are two wires dedicated for each coil; one is battery feed which usually comes from the distribution center, and the other one for the coil driver circuit from the PCM. The PCM grounds or ungrounds the circuit to activate or deactivate the coil.

Symptoms

Symptoms of a P0091 Arista Passy diagnostic trouble code may include:
Place of P0091 in engine

Possible Causes :

  • Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
  • Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
  • Some aftermarket accessories and performance modifications

Common Misdiagnoses

  1. IC Circuit High Voltage Problem
  2. Control Module Throttle Actuator Position Performance Problem
  3. Air Conditioning (A/C) Clutch Feedback Circuit High Voltage Problem
  4. Cruise Vehicle Speed/Set Speed Difference Too High Problem
  5. PCM Stack Overrun 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.

Process Tips

Diagnostic trouble code P0091 Arista Passy 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 P0091 Arista Passy.

Fortunately, P0091 Arista Passy is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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