Parts for your 2001 Mitsubishi Pajero-Oxygen sensor

2001 Mitsubishi Pajero oxygen sensor — what’s fitted and what to do about it

Based on reputable technical sources, the oxygen sensor is relevant to some 2001 Mitsubishi Pajero models and not to others. The factory NM-series service manual (Engine Electrical section) specifies heated oxygen sensors (HO2S) for the 3.5‑litre 6G74 petrol V6, mounted before and after the catalytic converter for closed‑loop fuel control and catalyst monitoring. The Mitsubishi ASA electronic parts catalogue also lists HO2S components against VINs with the 6G74 engine, and major aftermarket catalogues from Bosch and NGK/NTK carry direct‑fit oxygen sensors for 2000–2002 Pajero 3.5 petrol. Conversely, the 3.2‑litre 4M41 DI‑D diesel of the same year does not show a lambda/oxygen sensor in the 4M41 engine manual or parts listings, diesel fuelling is managed via MAF, MAP/boost, rail pressure and EGR feedback, not an O2 sensor.

For 2001 Pajero petrol owners, the oxygen sensor quietly does a power of work. Sitting in the exhaust stream, it measures how much oxygen is left in the burnt gases so the ECU can trim fuelling on the fly. That keeps the air‑fuel mix right where it should be, helping the V6 run smoothly, use less petrol, and keep emissions in check. The downstream sensor keeps tabs on catalytic converter efficiency, so the whole after‑treatment system does its job.

With age, contamination and heat cycles, O2 sensors get lazy or fail outright. When they do, the ECU can swing rich, economy drops, and the converter can cop a hiding. Many tech references peg typical life for heated sensors at around 160,000 km, sometimes less in harsh stop‑start or dusty conditions. Proactive replacement on older, higher‑kilometre Pajeros is cheap insurance.

• Common clues: higher fuel use, rough idle, flat spots, sooty tailpipe, or the MIL on with codes like P0130–P0161.
• Upstream sensors influence fuelling the most, downstream sensors monitor the cat.
• Mixing up “Bank 1/2” or “Sensor 1/2” is a classic pitfall—check a wiring diagram or the service manual first.

Servicing tips: use a proper O2‑sensor socket and let the exhaust cool to warm, not blazing hot. Most quality replacements arrive with anti‑seize on the threads—if so, don’t add more. Avoid touching or contaminating the sensing tip. After fitting, clear fault codes and check for exhaust leaks ahead of the sensor (leaks skew readings). Stick to trusted brands (Denso, NGK/NTK, Bosch) and verify the connector matches your VIN/market. If the Pajero has multiple sensors, replace them in pairs on high‑km vehicles to keep trims even.

Driving a 2001 Pajero diesel? Relax—there’s no oxygen sensor to service. Put your effort into a healthy MAF, clean EGR/intake, good fuel filtration, and regular checks for boost leaks.

• Does the 2001 Mitsubishi Pajero diesel have an oxygen sensor?
  No. The 3.2‑litre 4M41 DI‑D diesel doesn’t use a lambda/O2 sensor. Diesel fuelling is governed by air‑mass, boost and pressure sensors, so there’s no O2 sensor to replace or maintain on those models.
• How many oxygen sensors are on a 2001 Pajero 3.5 V6?
  Typically two—one before and one after the catalytic converter on many AU/NZ‑spec NM V6s. Some markets or trims can have additional sensors. The safest bet is to check by VIN or physically count the connectors on the exhaust.
• When should the oxygen sensors be replaced on the V6?
  As a guide, around 160,000 km or when symptoms/codes appear. Harsh use can shorten life. If the Pajero has racked up big kilometres, pre‑emptive replacement of tired upstream sensors can restore fuel economy and drivability.