B0121 Opel P+1200 Diagnostic Trouble Code

B0121 Opel P+1200 code definition:
B0121 is a kind of OBD-II Diagnostic B-Body Diagnostic Trouble Code for Opel P+1200.

B0121 Opel P+1200 is defined as Knock Sensor Circuit Range Performance (Bank 1 or Single Sensor). This refers to camshaft timing, which in this case is over-retarded. Any code that causes the vehicle's engine to die while running should be fixed as soon as possible, as it can be dangerous for both the vehicle and the passengers of the vehicle.

Symptoms

Symptoms of a B0121 Opel P+1200 diagnostic trouble code may include:
  • Poor acceleration
  • Cherry red hot catalytic converter
  • Possible spark knock (detonation / pre-ignition)
  • Hesitation upon acceleration
Place of B0121 in engine

Possible Causes :

  • Some aftermarket accessories and performance modifications
  • A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
  • A large air leak at or near the number one oxygen sensor would also cause a lean mixture.

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 :

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. 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. Now, clear the codes and test-drive the vehicle to see if the code is reset.

Process Tips

Diagnostic trouble code B0121 Opel P+1200 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 B0121 Opel P+1200.

Fortunately, B0121 Opel P+1200 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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