OBD II Engine Diagnostics: Not as Simple as it Seems
Anybody can plug a scan tool into a vehicle and read codes. But do they know what the codes mean, how to diagnose the fault or, most importantly, how to fix the vehicle? The problem with reading OBD II codes is that the code tells you only that a fault has occurred. It does not
Catalytic Converter Diagnosis
The catalytic converter is probably the most important emission control device on a vehicle because it cleans up the pollutants in the exhaust. Thanks to fuel injection, oxygen sensors in the exhaust manifolds, and a feedback fuel control system, emissions are kept to a minimum. Even so, some pollution is still produced and must be
Oxygen Sensors: Are You Up to Date on the Latest Designs?
If you’re a technician who works on late-model import vehicles and diagnoses engine performance and emissions problems, you probably have a good understanding of how oxygen (O2) sensors work. You know that all late-model engines have at least one or more “upstream” O2 sensors in the exhaust system to monitor the air/fuel mixture, and one
‘Sensing’ Problems: A Drop in Fuel Economy and Higher Exhaust Emissions Signal O2 Sensor Replacement
Oxygen sensors have been used for more than a quarter of a century, dating back to 1980 when the first computerized engine control systems appeared. Part of the fuel management system, the oxygen (O2) sensor monitors unburned oxygen in the exhaust. The powertrain control module (PCM) uses this information to determine if the fuel mixture
PCV Service: Helping an Engine Catch Its Breath
I’m certain that each and every one of you have, at some time in your life, experienced the horrific event of having the wind knocked out of you. If you can remember back to the first time it ever happened, before you knew that you would, in fact, breathe again, it was like you were
Diagnostic Solutions: Air/Fuel Ratio Sensors
Diagnose and Solve the Root Cause of Sensor Failure Before Sensor Replacement
P0401 Codes and EGR Issues
As emission controls got tighter, and with the advent of OBD II, things started to change. We not only saw additional driveability complaints, but we also had the check engine light (CEL) telling the customer there was an emissions failure that had to be dealt with for the good of the environment and, in most
Mischievous Cats
By definition, a catalytic converter should last the lifetime of the vehicle. It can last this long because a catalyst is something that, just by being present, causes a reaction to other materials without itself being a participant in the reaction. However, real life has proven that the life span of a catalytic converter varies
Oxygen Sensors: Pulse Measurement
Watching an oxygen sensor output on an oscilloscope is like watching a sporting event on television. You get to see the action, but can do nothing about it as it happens. Sometimes you miss the action and want an instant replay. It was a bad call. You saw the interference. If the referee didn’t see
Diagnostic Dilemmas: Symptom Diagnosis…The Journey Begins
When I first began my automotive career way back in 1957, the symptoms of an ailing engine were very apparent. A carburetor with a worn accelerator pump, for example, would characteristically stumble on acceleration and a closed-up set of distributor contact points would cause the engine to become very sluggish. Low fuel pressure caused by
When Should You Replace an Oxygen Sensor?
Is there a mileage or time requirement for oxygen sensor replacement? Simple answer: No. Oxygen sensors were first used for fuel trim and emissions in the late 1970s and into the mid 1990s. A single sensor was installed into the exhaust stream to modify fuel delivery and maintain catalytic converter efficiency. Beginning January 1, 1996,
Diagnostic Solutions: Oxygen Sensor Diagnostics
Once considered leading-edge technology, today’s oxygen sensor has become a commonplace service item on modern vehicles. Popularly introduced in the 1970s, the Lambda or, as it’s more popularly known, the oxygen sensor, rapidly became standard equipment as it’s a vital component of closed-loop or feedback fuel control technology. By using a voltage input from the