OBD II Archives - Page 4 of 5 - TechShop Magazine
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

EGR Issues: Dealing with P0401 Codes

ht=”245″ alt=”” align=”right” /> 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

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

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,

Troubleshooting MIL Issues: OBD II & “CAN” Scan Tool Diagnostics

The Malfunction Indicator Lamp (MIL) is one of the most misunderstood warning lights on vehicles today. Most motorists have no idea what the light means or why it’s on. Some think the MIL light is an oil change reminder light. Others realize something must be amiss to cause the light to come on, but don’t

Up in Vapor

Gasp! It’s the “Gas Cap Code”! Oh no, you just pulled a code P0422, evaporative purge small leak detected… Here goes the needle in the haystack syndrome. So what do you do? Recommend a new gas cap and ship it? Well you could do that, but would that be in your or your customer’s best

Diagnostic Dilemmas: The Pressures of Intake Manifold Vacuum Tests

Several years ago, a retired school teacher brought in a 1994 Chevrolet S-10 Blazer that had developed an intermittent rough idle condition. Although a rebuilt engine had been installed a year before, and all of the wiring and vacuum hoses looked as if they were in factory condition, I took nothing for granted. An ignition