P121E MINI – Disconnection of the Linear Oxygen Sensor Line from the Nitrogen Oxide Sensor

P121E MINI Possible Causes

  • Faulty nitrogen oxide (NOx) sensor Linear oxygen sensor
  • Nitrogen oxide (NOx) sensor Linear oxygen sensor harness is open or shorted
  • Nitrogen oxide (NOx) sensor Linear oxygen sensor circuit poor electrical connection

How to Fix P121E MINI Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or engine warning light soon)

P121E MINI Meaning

The Engine Control Module (ECM) monitors the nitrogen oxide (NOx) sensor linear oxygen sensor. The ECM sets the OBDII code when the nitrogen oxide sensor linear oxygen sensor does not meet factory specifications.

P121F – Linear Oxygen Sensor Short Circuit of the Nitrogen Oxide Sensor

Code P121F: Causes, Symptoms, and Solutions

Meaning of Code P121F
The Engine Control Module (ECM) detects a malfunction in the linear oxygen sensor associated with the nitrogen oxide (NOx) sensor. This code is triggered when the sensor values do not meet the manufacturer’s technical specifications.

Possible Causes

  1. NOx Sensor Failure: The nitrogen oxide sensor may be damaged or out of service.
  2. Electrical Issue in the Oxygen Sensor Harness:
  • Open circuit or short circuit in the harness.
  • Damaged connectors (broken, bent, corroded, or disconnected pins).
  1. Poor Electrical Connection: Faulty contacts between the NOx sensor and the linear oxygen sensor circuit.

Common Symptoms

  • Illumination of the engine warning light (or warning message).
  • Possible disruptions in engine performance or the anti-pollution system (depending on the severity of the fault).

Diagnostic and Repair Procedure

  1. Visual Inspection:
  • Check the oxygen sensor harness and associated connectors.
  • Look for signs of corrosion, cut wires, or deformed pins.
  1. Check Electrical Connections:
  • Ensure the NOx sensor and oxygen circuit connectors are clean and securely fastened.
  1. NOx Sensor Test:
  • Use a diagnostic tool to analyze real-time data and compare it with reference values.
  1. Replacement if Necessary:
  • If the sensor or harness is faulty, replace the affected component.

Tip: After repair, clear the code with an OBDII scanner and perform a road test to confirm the fault is resolved.

Note: If unsure about technical skills, consult a professional equipped with specialized diagnostic tools.

P121F BMW – Linear Oxygen Sensor Short Circuit in Nitrogen Oxide Sensor

BMW Code P121F: Linear Oxygen/NOx Sensor Fault
(Bank 1 or 2, depending on configuration)

Meaning of Code P121F

The P121F code specific to BMW vehicles indicates a performance or communication problem between the nitrogen oxide (NOx) sensor and the linear oxygen sensor. The ECM (Engine Control Module) detects a discrepancy between the measured values and the manufacturer’s specifications, often related to emissions control systems (Euro 6/SCR standards).

Common Symptoms

  • 🚨 Check Engine Light illuminated.
  • 📉 Reduced performance (limp mode activated).
  • ⚠️ High pollutant emissions (risk of failing emissions test).
  • ⛽ Increased fuel consumption.

Possible Causes on BMW

  1. Faulty NOx Sensor:
  • Internal wear, contamination by residues (soot, fuel).
  • Common on BMW diesel models (e.g., F30 320d, G30 520d).
  1. Electrical Problems:
  • Damaged wiring harness: Cut wires, short circuits (vibration, rodents).
  • Oxidized connectors: Moisture, corrosion (typical for vehicles driven in salty environments).
  1. ECM Software Failure:
  • Software update required (calibration errors).

Diagnostic Procedure

Step 1: Reading Codes and Real-Time Data

  • Use a compatible BMW scanner (e.g., ISTA/D, INPA) to:
  • Check NOx sensor values (mg/km of NOx at idle and under load conditions).
  • Analyze linear oxygen sensor voltages (0.1–0.9V in closed loop).

Step 2: Visual Inspection

  1. Locate the NOx sensor:
  • Typically located after the SCR catalyst on diesel models.
  1. Check the wiring harness and connectors:
  • Look for signs of burning, chafing against hot components (turbo, exhaust).

Step 3: Electrical Test

  • Measure the resistance and continuity of the wiring harness with a multimeter:
  • Expected resistance: 5–100 Ω (depending on model).
  • Supply voltage: 12V (ignition ON).

Step 4: Cleaning/Replacement

  • If the sensor is contaminated, use a specific NOx sensor cleaner.
  • If a failure is confirmed, replace with an OEM sensor (e.g., Bosch, Continental).

Repair Solutions

  • 🔧 Replacing the NOx sensor: Expect €300–€800 (part + labor).
  • 🔌 Repairing the wiring harness: Perform a sealed solder joint or replace the entire harness.
  • 💻 ECM Update: Performed at a BMW dealership using ISTA/P software.

Prevention

  • Avoid repeated short trips (prevents premature sensor fouling).
  • Use quality fuel (high cetane rating for diesel).
  • Have the SCR system checked regularly (AdBlue injection, particulate filter).

Common Mistakes to Avoid

  • ❌ Ignoring the Check Engine Light: Risk of SCR catalyst damage.
  • ❌ Using low-quality sensors: Software incompatibility or reduced lifespan.

In Summary: Code P121F on a BMW often points to a NOx sensor or electrical issues. Precise diagnosis with specialized tools is essential to avoid costly repairs. Consult a BMW specialist if you lack the technical skills.

P121F MINI – Linear Oxygen Sensor Short Circuit of the Nitrogen Oxide Sensor

P121F MINI Possible Causes

  • Faulty nitrogen oxide (NOx) sensor Linear oxygen sensor
  • Nitrogen oxide (NOx) sensor Linear oxygen sensor harness open or short circuit
  • Nitrogen oxide (NOx) sensor Linear oxygen sensor circuit poor electrical connection
 

How to fix P121F MINI code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

 
 

Possible Symptoms

  • Engine light on (or engine service warning light soon)
 

P121F MINI Meaning

The engine control module (ECM) monitors the nitrogen oxide (NOx) sensor linear oxygen sensor. The ECM sets the OBDII code when the nitrogen oxide sensor linear oxygen sensor does not meet factory specifications.

P1220 – Throttle Actuator Control System Malfunction

Error Code P1220: Possible Causes

The error code P1220 can be triggered by several factors, including:

  • A faulty throttle position (TP) sensor.
  • A throttle position (TP) sensor wiring harness with a break or short circuit.
  • A poor electrical connection in the throttle position (TP) sensor circuit.

How to Resolve Code P1220?

The first step is to carefully examine the potential causes mentioned above. Visually inspect the wiring and connectors associated with the TP sensor. Check for any damage to the components and ensure that no connector pins are broken, bent, pushed in, or corroded.

Associated Symptoms

The appearance of code P1220 may be accompanied by the following symptom:

  • The engine light comes on (or a “check engine soon” warning light may activate).

Meaning of Code P1220

The throttle position (TP) sensor is mounted on the throttle body of the throttle actuator control (TAC) assembly. It actually incorporates two separate throttle position sensors in a single housing. To connect the TP sensor assembly to the TAC module, two separate signal circuits are used, along with a low reference circuit and a 5-volt reference circuit. The signal voltage emitted by the TP sensor increases proportionally to the throttle opening. The TP sensor signal circuit is powered by a 5-volt reference voltage.

P1220 AUDI – Cylinder 8 Injector Circuit Short to Positive

P1220 AUDI Possible Causes

  • Faulty fuel injector
  • Fuel injector harness is open or shorted
  • Poor electrical connection in fuel injector circuit

How to Fix P1220 AUDI Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1220 AUDI Meaning

Cylinder 8 Injector Circuit Short to Positive is the generic description for Audi P1220 code, but the manufacturer may have a different description for your vehicle model and year. Currently, we don’t have more information about the Audi P1220 OBDII code.

P1220 BUICK – Throttle Position Sensor 2 Circuit

P1220 BUICK Possible Causes

  • Faulty throttle position sensor (TP)
  • Throttle position sensor (TP) harness is open or shorted
  • Poor electrical connection in throttle position sensor (TP) circuit

How to Fix Code P1220 BUICK?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or engine service warning light soon)

P1220 BUICK Meaning

The throttle position sensor (TP) is mounted on the throttle body of the throttle actuator control (TAC) assembly. The sensor is actually 2 individual throttle position sensors in 1 housing. Two separate signal circuits, one low reference circuit and one 5-volt reference circuit are used to connect the TP sensor assembly and the TAC module. The TP sensor signal voltage increases as the throttle opens. The TP sensor signal circuit is pulled up to a 5-volt reference voltage.

P1220 CADILLAC – Throttle Position Sensor 2 Circuit

P1220 CADILLAC Possible Causes

  • Faulty throttle position sensor (TP)
  • Throttle position sensor (TP) harness is open or shorted
  • Poor electrical connection in the throttle position sensor (TP) circuit

How to Fix Code P1220 CADILLAC?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or engine service warning light soon)

P1220 CADILLAC Meaning

The throttle position sensor (TP) is mounted on the throttle body of the throttle actuator control (TAC) assembly. The sensor is actually 2 individual throttle position sensors in 1 housing. Two separate signal circuits, one low reference circuit and one 5-volt reference circuit are used to connect the TP sensor assembly and the TAC module. The TP sensor signal voltage increases as the throttle opens. The TP sensor signal circuit is pulled up to a 5-volt reference voltage.

P1220 CHEVROLET – Throttle Position Sensor 2 Circuit

P1220 CHEVROLET Possible Causes

  • Faulty throttle position sensor (TP)
  • Throttle position sensor (TP) harness is open or shorted
  • Poor electrical connection in throttle position sensor (TP) circuit
 

How to Fix P1220 CHEVROLET Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

 
 

Possible Symptoms

  • Engine light on (or engine service warning light soon)
 

P1220 CHEVROLET Meaning

The throttle position sensor (TP) is mounted on the throttle body of the throttle actuator control (TAC) assembly. The sensor is actually 2 individual throttle position sensors in 1 housing. Two separate signal circuits, one low reference circuit and one 5-volt reference circuit are used to connect the TP sensor assembly and the TAC module. The TP sensor signal voltage increases as the throttle opens. The TP sensor signal circuit is pulled up to a 5-volt reference voltage.

P1220 FORD – Series Throttle Control Fault Detected

P1220 FORD Possible Causes

  • Faulty throttle control motor
  • Throttle control motor wiring harness is open or short-circuited
  • Poor electrical connection in the throttle control motor circuit

How to Fix P1220 FORD Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or engine service warning light soon)

P1220 FORD Meaning

Series throttle control fault detected is the generic description for Ford code P1220, but the manufacturer may have a different description for your vehicle model and year. Currently, we have no further information about the Ford P1220 OBDII code.