SENSING THE TROUBLE
CAMBIARE elaborates on the workings of an important element within the engine management system–Exhaust Gas Temperature Sensors (EGTS) to help factors develop brand new profit streams.
Vehicle electronics specialist Cambiare understands the importance of introducing such products that are relevant to the current aftermarket demands or help meet various regulatory requirements placed on modern engine systems. Keeping this in mind, Cambiare has recently introduced a short range of oil level sensors, while extending on its successful range of exhaust gas temperature sensors (EGTS).
EXHAUST GAS TEMPERATURE SENSORS (EGTS)
With emission standards becoming increasingly stringent, vehicle manufacturers are developing newer technologies to meet the legislations necessitating the release of cleaner exhaust gases. An EGTS measures the temperature of the exhaust gas which is monitored by the ECU to help prevent damage to components.
FORM AND FUNCTION
Cambiare’s current range of over 100 EGTS covers 2.6m vehicles in the UK and offers two variations: positive temperature coefficient (PTC) and negative temperature coefficient (NTC) sensors. Typically measuring temperatures up to 900°C in the exhaust system, the resistance of the EGT sensing element alters with the change in exhaust temperature.
Whilst the more common PTC sensors function by increasing their resistance with increasing exhaust gas temperature, the NTC sensors decrease their resistance with a subsequent temperature increase. This resistance is registered by the ECU in order to take necessary actions, ranging from protection from thermal overload during DPF regeneration and selective catalytic reduction (SCR) to exhaust gas recirculation and overall engine combustion.
FAULTS AND FAILURE
A faulty sensor can drift out of tolerance limits and give incorrect readings, causing over-fuelling issues during regeneration, due to the process being prolonged. PTC EGTS are designed in such a way that it will continue to relay misinformation to the ECU without setting a diagnostic trouble code, making it seem like the DPF is regenerating within its permitted temperature range and delay the detection of thermal overload. Many a time, a DPF is wrongly assessed to be faulty, when it’s actually the failed EGTS which needs replacement.
NTC sensors, on the other hand, are designed with two wires bonded to a ceramic cell. With time, this bond can break and the sensor goes into an open circuit, triggering the engine check light – an easy fault to diagnose.
EGTS are primarily prone to damage during exhaust component replacements and should therefore be replaced simultaneously with a DPF and/or exhaust, rather than waiting for the dashboard warning light to illuminate.
Other causes include:
• Severe vibration that can break the connection of internal wires.
• Excessively high temperatures (T>900°C) causing resistance deviation of the thermistor element.
• Severely bent wires (where bending diameter<20mm) that can cause wire breakage.
• Contamination from oil, antifreeze or poor fuel quality.
Timely diagnosis and replacement of a defective EGTS prevents damage to the DPF and subsequent engine damage.
CAMBIARE FOR CHANGE
Working in critical environment makes it vital that the replacement EGTS is OE quality, offers engine control, over-temperature protection and a long life in extreme conditions of temperature, vibration and contamination. Made of high temperature resistant metals and ceramics, Cambiare EGTS afford high mechanical, thermo-mechanical and physiochemical stability.
• Extremely wide operating temperature range
• High long-term stability
• Standardised characteristic curve
• Short response time in transient conditions
As well as Cambiare’s OE quality assurance and a wide coverage through such a short range, there are plans to extend the range further, depending on incoming market demands.
VALUE ADDED SERVICES
• All parts are OE quality and offer 2 year/30,000 mile warranty.
• Parts catalogued on Cambiare website: www.cambiare-ve.com as well as MAM Autocat+ and the F:Drive; search path: Fuel & Engine Management>Engine Management & Fuel Inj. Parts> Oil Level Sensors or Exhaust Gas Temperature Sensors.
• Cambiare offers technical support via a devoted hotline no. 0845 543 8280.
Speak to a local Cambiare representative for more information.