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Lambda Sensor fault-finding boosts workshop customer satisfaction


DENSO is helping workshops identify signs of faulty Oxygen Sensors with expert servicing tips As a leading manufacturer of Oxygen Sensors, DENSO is providing workshops with expert fault-finding tips to improve fuel efficiency and reduce exhaust emissions for environmentally-aware customers.


A combination of ever-tightening environmental regulations and environmentally-aware motorists over the last decade has made Lambda Sensors amongst the most important components to service.

With OE-quality Lambda Sensors able to dramatically reduce exhaust emissions and optimise engine efficiency, keeping sensors in top condition, or efficiently replacing them has become an opportunity to upsell and ultimately earn a reputation for outstanding customer service.

However, despite the opportunities for workshops even the best technician can be let down by a lack of knowledge on how to correctly and comprehensively service Lambda Sensors.

As one of the leading suppliers of OE and aftermarket Lambda Sensors, DENSO has revealed some of its top tips to providing customers with the perfect service:

Warning Signs

Technicians should firstly keep note any physical signs of a faulty Lambda Sensor – these could be flagged by the motorist themselves or through a diagnostic check. Typical symptoms include high fuel consumption, rough engine running, poor emissions performance or simply via the Diagnostic Trouble Code (DTC).

To be as proactive as possible, performing a Systematic Diagnosis can help provide a near full-proof service and routinely identify any Lambda Sensor defects:

1.    Check service history

A first course of action should be checking for components that may have been replaced in the last service or incorrectly fixed. Also check if any connections were not refitted, or if the wrong parts have been used. Pay particular attention to anything which could affect Lambda Sensors, including EGR valves, fuel injectors and exhausts.

2.    Visual inspection

Check under the bonnet for any exhaust leakage. This process takes little time, but could potentially save hours.

3.    DTCs

Check for Diagnostic Trouble Codes if this was not done before.

4.    Live tests

Perform live tests and check the exhaust system for leakage. Then use a live test and start the O2 sensor only, to check how long it takes for the signal to give a reliable hi-low oscillating signal. Also test the heater resistance at room temperature; the heater power from the car and the heater current during engine warm-up. If that fails to provide a solution, compare with other sensor signals during idle and raised (2500) RPM.

5.    Sensor inspection

The tip of the sensor should be a dull grey in colour. If discoloured to red, it may signify a contamination by fuel additives which can block the sensor and prevent it from functioning properly. In addition, check for damage to wires and connectors to the EMS system

6.    EMS inspection

Check other parts of the EMS, including MAF Sensors, the thermostat and fuel injectors for any exhaust leakage.

By performing a comprehensive sensor check service technicians can fix minor issues and learn when a sensor is in need of replacement. Fitting long-lasting OE quality prevents ensures a long-lasting replacement whilst providing an improved service that boosts customer satisfaction and in turn, retention.

Nick Thomas, Product Manager at DENSO Sales UK, commented: “One of the most important considerations for today’s motorists is the environment. Whilst that focus presents a challenge for workshops, it can offer even greater opportunity if technicians have the know-how to maintain those crucial components for engine efficiency.

“With green technology developing at a remarkable pace, it is easy to forget there are millions of vehicles on the roads which need to be properly maintained to deliver optimal engine efficiency and reduce exhaust emissions.”