OBD II Archives - Page 3 of 4 - Import Car
Tech Tip: Wave Dynamics for Headers and Pipes

Depending upon the market to which an import shop might be catering, the term “performance exhaust” can have two different meanings. The first market actively seeks out the throaty rumble and chrome-plated look as part of the street-driving scene. The second market installs an exhaust system that produces the most horsepower for a performance application. Sometimes the two markets are identical and sometimes they’re not.

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

Emissions Update: Understanding How Wide Ratio Air/Fuel (WRAF) Sensors Work

Instead of giving a simple rich/lean indication, wide ratio air/fuel sensors measure the “actual” air/fuel ratio. A WRAF sensor can measure mixtures that range from extremely rich to extremely lean (even straight air!). This ability allows the PCM to control fuel mixtures much more precisely, to handle much leaner fuel mixtures, to reduce emissions and

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

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

Mercedes: Addressing MIL Issues

‘Systems Operation’ Knowledge and Proper Equipment Saves Diagnostic Time and Speeds Repair Process It may not be a Mother-in-Law light, but the effect can be about the same. Just when you don’t want to see it, there it is! The Malfunction Indicator Light (MIL) has been around for more than 25 years, but since OBD

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

Foreign Affairs: VW P Codes — … Putting Out The MIL

After 10-plus years of dealing with OBD II, it should be apparent that we are on a learning curve that probably has no end. Almost daily we have a Volkswagen model come into the shop with a check engine light on, or a “state OBD II failure” form. Although we have the latest scanner software

Maintenance Essentials…, OBD II & Chassis Checks

All cars need maintenance. The fact is mechanical devices wear and fail in normal use, and deteriorate over time, so being able to diagnose a future failure has become a part of the automotive repair and service industry. Customers always ask how long it will be before a component will fail, and are usually not

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