Oxygen (Lambda) sensor

From WikiLEC
Jump to: navigation, search


The Oxygen (02) Sensor monitors the amount of unburnt oxygen which passes out of the engine through the exhaust manifold. This reading is then used by the ECM to determine the correct input fuel mixture. It is not the only sensor that controls fuel mixture, but it is regarded as the 'primary' sensor, because ultimately whatever is exhausted from the engine is the 'actual' result of the burnt mix - whereas all the other sensors read pre-burn factors such as air and coolant temperatures.

Oxygen Sensors only came into mainstream production use in the early-mid 90s, and hence not found on the N/A or SE Elan M100. However, it is possible to convert the SE to use an O2 Sensor.


The heater is powered from the no charge warning lamp connection on the alternator so that it is not heated until the engine is running. Note that if the no charge warning lamp is illuminated on the dash, the heater voltage will not be a full 12V. The output (0V referenced) is fed to the [ECU] pin D7 - see the Fed O2 Sensor Wiring Diagram

Replacement parts - All 3 wire exact replacements

The following appear to be currently available exact drop in replacements:

Bosch 13277

Bosch 15701

Walker 250-23127

Denso 234-3014

Replacement parts - Background

In the LEC repairs area, Jade and Nitro identified the Discount Auto #11039 as a direct replacement for Fed Elans, Doug also identified the Bosch #13277 and Charlie the NGK #21012. Rockauto also list the Bosch #15701 as a direct replacement.

Having dug around unsuccessfully on UK sites to find these part numbers, it looked like I was going to have to get one in from the US.

However, I happened upon one on a well known international auction site for a Rover 218 VVC. The only apparent difference is that the wires appear longer than the Elan's which are about 40cm long. Fortunately, a European Bosch number (10 numbers) was on the photograph so a quick search on 0 258 003 229 threw up the Just Lamba website whose details confirmed the Rover part appeared to have the right connector but that the lead length was 59cm. Never mind, 13 lines above it are the details for the 0 258 003 193 which has a lead length of 39cm. A further search of the part number throws up the 1300 Mk1 Mini from Seik for €24.

The European Bosch reference for the O2 sensor would appear to be 0 258 003 193 from a 1300 Mini {although I've just noticed it's four wire not three wire and the pins are spade rather than round ... bugger!} These alternatives should work but will require the plug to be rewired Also very useful information at Lucas Electrical

There are some other possible replacements listed at OxygenSensors.com under:
Year: 1991
Make: Isuzu
Model: Impulse
Sub-Model: RS
Engine: L4 cyl (1.6 L,1588)

The exact drop-in replacements suggested are:
Walker #250-23127 3-Wire
Denso #234-3014 3-Wire

Warning.png This site also lists a 'Universal' part #250-23000. Ignore this, as the fitting is not correct

Replacement parts, UK Sourced

Added by JonT in Feb 2011 (car is a May 1991 SE)

Googling for the 15701 Sensor in the UK seems to go nowhere, but this site: Advance Auto Parts gives a long list of cars that use that particular sensor. Bosch have an online parts catalogue. Using some of those cars suggested above (making sure you tick the "enlarge vehicle fleet to all countries") allows you to search for some of the cars on the list above. Taking say the Isuze Rodeo 2.6 gives part 0258003277 but that's only 340mm according to the Bosch site. Other than that, the plug looks right, and it's 3 wire. The Rodeo is also listed as using 0258005701. This is listed on the Bosch site as a 3 wire, 430mm O2 sensor, with a cross reference part number of 15701 - which is a direct fit as given above. Searching for the 10 digit part number on UK ebay produces a supplier (at a price!) who will supply a genuine 3 wire Bosch part. This seems to work as a direct fit with the correct connector with no extra work needed. Note that their auction page lists this as a 4 wire part (possibly because it's a 4 pin connector), but it's definitely the 3 wire part matching the part number that is supplied.


  1. Apply copious amounts of penetrating oil, heat and/or cold to get the old sensor out.
  2. Use an 18mm O2 sensor socket which has a slot up the side for the lead.
  3. Check that the thread in the exhaust system is clean and in good condition before attempting to install the new sensor. Don't drop any swarf into the pre-cat!
  4. Handle the sensor with care to prevent damage - dropping a sensor could inflict damage to the ceramic, which would not be apparent during installation.
  5. During production an anti-corrosion compound is applied to the threaded portion of the sensor body. This is a sensor friendly grease compound and no other anti-seize compounds should be used as they may contain ingredients that could poison the sensor elements. Do not use any other cleaning or anti-rust solvents near the sensor body as this could similarly affect the element.
  6. Remove the protection cap just prior to fitting. Screw the sensor into place by hand then tighten to the specified Torque settings ensuring that the wiring harness is not twisted as the sensor is screwed in.
  7. Secure the harness using the correct fixings, ensuring that the routing does not produce any kinks in the wires, touch any part of the exhaust system or other hot components and does not foul any rotating parts.
  8. Reconnect the harness connector.