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Nie, dziękuję Przekieruj mnie tamI am looking for the wiring to the O2 and NOX sensors for both 8 and 6 wire versions
• There is no global “standard” colour-code or pin sequence for 6- or 8-wire O₂ / NOx sensors – every OEM (Bosch, Continental, NGK/NTK, Denso, Delphi, etc.) and sometimes every vehicle platform uses its own connector mould, keying and colour set.
• What is common is the function assigned to each wire. The two tables below show the most frequently encountered automotive pin functions for:
– a 6-wire wideband O₂ or Gen-1/2 NOx probe, and
– an 8-wire sensor (usually a diesel NOx sensor or Bosch LSU-ADV wideband O₂).
| Typical 6-wire connector (Bosch LSU 4.9 / NGK AFX / Gen-1 NOx probe) Pin |
Function | Typical colour (Bosch) | Notes |
|---|---|---|---|
| 1 | Pump current + (IP+) | White | Controls O₂ ion pumping direction |
| 2 | Virtual ground / reference (VS) | Grey | ECU keeps ≈0.45 V reference |
| 3 | Heater – (H–) | Black | Low-side or PWM by ECU |
| 4 | Heater + (H+) | Red | Battery or ECU supply (9–16 V) |
| 5 | Calibration / trim resistor (RT) | Yellow | Individual sensor ID (≈30–300 Ω) |
| 6 | Pump current – (IP–) / common | Green | Returns pump current |
| Typical 6-wire NOx probe (Bosch Gen-2, probe side of module) Pin |
Function | Notes |
|---|---|---|
| 1 | O₂ pump cell + (pre-cell) | |
| 2 | Vs reference | |
| 3 | Heater – | |
| 4 | Heater + | |
| 5 | NOx pump cell + (measure-cell) | |
| 6 | Common return for pump cells |
| Typical 8-wire connector (diesel NOx sensor assembly, harness to vehicle) Pin |
Function | Typical colour | Notes |
|---|---|---|---|
| 1 | Battery B+ (Terminal 30, unswitched) | Red | +12 V / +24 V, fused (≈2–4 A) |
| 2 | Ignition / Wake-up (Terminal 15) | Violet | Switched supply, enables module |
| 3 | Chassis/logic ground | Brown | 0 V reference for electronics |
| 4 | Power ground (heater) | Black | Separate high-current return |
| 5 | CAN-High | Green | 500 kbit/s differential bus |
| 6 | CAN-Low | Yellow | |
| 7 | Shield / Drain or private CAN-H | Bare | Optional, OEM-specific |
| 8 | Shield / Drain or private CAN-L | Bare |
| Typical 8-wire Bosch LSU-ADV wideband O₂ (rare, motorsport) Pin |
Function | Notes |
|---|---|---|
| 1 | IP+ (pump) | |
| 2 | VS (virtual ground) | |
| 3 | H– | |
| 4 | H+ | |
| 5 | RT (trim resistor) | |
| 6 | IP– | |
| 7 | UN+ (Nernst +) | |
| 8 | UN– (Nernst –, differential) |
Use the tables as a functional guide only; always confirm the exact pin numbering and colours in the factory wiring diagram for your specific model/year/engine.
Sensor construction & why so many wires
• A wideband O₂ sensor contains two electro-chemical cells (Nernst & pump), a diffusion chamber and a ceramic heater. The ECU must:
– keep the Nernst cell at ≈450 mV (stoichiometric reference),
– sense the pump current required to do so (proportional to λ).
• A NOx sensor is even more complex: an upstream O₂ pump cell removes excess O₂, a catalytic chamber splits NOx → N₂+O₂, and a second pump cell measures the liberated O₂. Because of the high energy budget and signal conditioning, most NOx probes carry only heater and pump leads; a small control module is bolted to the sensor body and talks to the vehicle over CAN.
6 wires vs. 8 wires
• Six leads are all that is electrically necessary for a stand-alone wideband sensor: two for the heater, two for the pump loop, one virtual ground and one calibration ID.
• Eight leads appear in two situations:
– when a differential Nernst measurement is wanted (UN+/UN–) for higher CMRR (e.g. Bosch LSU-ADV), or
– when the sensor assembly includes data communication (CAN, LIN) and separate power/grounds (typical diesel NOx sensors).
Heater requirements
• Zirconia elements only become active above ~650 °C. An integrated Pt heater draws 1–3 A during cold start; the ECU modulates it to keep 700–850 °C cell temperature. A good cold resistance reading is 1.5–8 Ω depending on sensor type.
Signal integrity
• Pump current wires carry only ±2 mA but must be noise-free. OEM looms use twisted, overall-shielded pairs tied to ECU analog ground at one point.
• CAN pairs for NOx modules require 60 Ω differential bus impedance and < 40 pF/m capacitance; damaged shielding often causes U029D / P2200 trouble codes.
Trim resistor (RT)
• Laser-trimmed, unique to each sensor. If the connector is cut off and a “universal” plug spliced, the ECU reads the wrong resistance → mixture errors of 3–5 %.
• Euro-7 and EPA27 proposals push toward combined O₂–NOx multifunction probes (Bosch LNT-NOx4). Expect 8–10 conductors or single-wire SENT/UART outputs to reduce harness bulk.
• OEMs are moving high-temperature electronics out of the probe and onto the chassis rail to survive >900 °C exhaust positions (Gen-4 Continental NOx).
• LIN-bus variants for low-cost gasoline particulate filters (GPF) start appearing in 2024 MY vehicles.
• Electrical analogy: think of the pump cell as a bidirectional constant-current source controlled by the ECU; the Nernst cell voltage is the feedback node.
• For NOx, add a second pump whose current is proportional to NOx ppm ≈ \(k \cdot I_{\text{pump,NOx}}\).
• Tampering with emission sensors or fitting non-type-approved parts can violate Clean Air Act (USA), Regulation (EU) 2018/858, and local MOT/inspection regimes.
• Data lines (CAN) carry VIN, sensor serial and hours-of-operation – manipulating them may breach anti-tampering laws.
Possible challenges & fixes
• “P0036 / P2202 after install”: missed ground pin – verify pin 3 or 4 continuity.
• Heater opens after 60 s: loom routed too close to down-pipe → use glass braid sleeve.
• Colour examples given are Bosch convention; Denso and Delphi often invert red/black for heater.
• 24 V commercial-vehicle sensors use identical pinouts but different module firmware – do not mix 12 V and 24 V parts.
• SAE papers: 2022-01-0561 “Latest Generation NOx Sensor Module Architecture.”
• Bosch “LSU-ADV Application Note” (free download after NDA).
• ETAS INCA-7 tutorial for live pump-current tracing.
• ISO 19689-3 (draft) – future unified connector coding for exhaust-gas sensors.
Multi-wire exhaust-gas sensors follow functional pin conventions even though colours vary.
– 6-wire O₂ / NOx probes carry: heater ±, pump ±, reference, and a calibration or second pump lead.
– 8-wire assemblies add either a differential Nernst pair (wideband) or vehicle-level power/ground and CAN (NOx).
For any repair, locate the exact OEM connector view, respect the trim resistor, and protect twisted/shielded pairs. Mis-wiring can destroy the sensor or ECU within seconds.
