When the auto diagnostics work is done, your shop must provide:

1. The auto diagnostics shop ID number.
2. The auto diagnostics and repair work description.
3. The total price charged for auto diagnostics labor and parts.

Confirm warranties at the auto diagnostics shop before you leave.

For your protection, the warranty document should include the following:

1. The auto diagnostics shop’s license number, contact information and physical address.
2. Description on what's covered by the automotive diagnostics service, including reworking or cash back.
3. Instructions for taking action on the auto diagnostics warranty.
4. The length of time for which the vehicle troubleshooting services warranty is active.
5. All terms, limitations and exclusions should be listed clearly on the proof of warranty document.

The following items are some common auto diagnostic issues handled by local automotive troubleshooting services in Contra Costa County.

Complete Auto Diagnostics
Local auto troubleshooting shops can perform complete auto diagnostic tests and print out a complete report with a set of codes that outline all found problems. Automotive diagnostic tests can diagnose ignition timing problems, excessive buildup in the engine, fuel injector problems, ignition coil diagnostics, exhaust system diagnostics, fuel pressure testing, vehicle air flow diagnostics, auto sensor circuit diagnostics, engine RPM levels, auto coolant temperature, crankshaft problems, camshaft position and the throttle opening malfunctions among other problems.

Auto Electrical Diagnostics
Dimming lights, trouble starting the car, sputtering and other issues can be signs of auto electrical problems. Auto electrical diagnostics test the electrical systems within the vehicle and give unique codes for each type of auto electrical malfunctions possible.

Auto Troubleshooting
General troubleshooting diagnostics are run to test engine oil sensors, auto alternator diagnostics, overheating problems and other car trouble diagnoses in domestic and foreign cars.

Auto Engine Diagnostics
Cars with engine trouble can have auto engine diagnostics run to narrow down the trouble to the underlying problem. Doing this preventatively or when small auto engine problems occur can prevent auto engine failure and more expensive problems down the road.

Auto Starter Diagnostics
Glitchy starters, choking, sputtering and failure to start are some signs that your vehicle may need auto starter diagnostic tests. These can pinpoint the origin of the auto starter problems, and can give your mechanic a clear path to follow to repair your auto starter problems.

Exhaust System Diagnostics
Lit check engine lights often are a sign of exhaust system problems. Troubleshooting can narrow down the codes to outline the exact exhaust system failure or trouble. This can prevent harmful gasses or pollution to be unduly released into the air and can help your car run more cleanly and efficiently.

On Board Diagnostics Checkup
On board diagnostics, including OBD I and OBD II, are the on-board diagnostic systems that point out potential problems in many newer-model vehicles. OBD diagnostic checkups are easy to run with the proper troubleshooting computers and codes.

Auto Air Conditioning Diagnostics
These diagnostic tests can give you the details on your auto air conditioning performance. Auto AC diagnostics may test the cooling system, coolant levels and AC refrigerant levels.

Check Engine Light Diagnostics
Check engine light diagnostics are some of the most common automotive troubleshooting codes run. Check engine lights can be triggered by several problems, but commonly pertain to auto emissions trouble. Auto exhaust system diagnostics are often run to rule out any serious problems with the exhaust systems.

Automotive Cooling System Diagnostics
Auto engine cooling and auto AC systems may need auto diagnostics from time to time to keep tabs on their function and any underlying problems. Automotive cooling system diagnostics can help your mechanic diagnose problems that are otherwise hard to troubleshoot.

Below are some auto troubleshooting terms which may be of help in understanding diagnostic services:

auto diagnostics
Discovering the exact cause of what's wrong with your car. Auto diagnostics now-days especially means on-board diagnostics (OBD) readable from each car's individual computer, for smog control purposes.

Also known as: diagnostic, auto diagnostic, OBD, OBDII, OBD2

auto diagnostic equipment
The diagnostic tools for reading the OBDII diagnostic trouble codes from your car's computer. This can be done with a diagnostic code reader or a diagnostic scan tool.

Also known as: diagnostic, diagnostic tools, auto diagnostics, OBDII diagnostic scan tool

auto diagnostic scan
The process of reading your car's computer, or PCM, for diagnostic trouble codes indicated by the Check Engine Light coming on. The diagnostic scan is done with an OBD diagnostic tool known as a scan tool.

Also known as: diagnostic tool, OBD diagnostic scan tool

auto diagnostic standardization
One of the main purposes of OBDII. In 1996, OBDII brought standardized connectors, standardized protocols, and other standardized elements to improve diagnostics for emission problems.

catalytic converter failure
One of the main causes of OBD diagnostic failure codes, Check Engine Light displays, and emission test failures. The catalytic converter turns various exhaust air pollutants, including carbon monoxide (CO) and nitrogen oxides (NOX), into harmless carbon dioxide (CO2) and water.

Check Engine Light
The result of OBD diagnostic trouble codes. When the Check Engine Light comes on, also known as the Malfunction Indicator Lamp, you have problems with your car's emission control system recorded in your car's on-board diagnostic (OBD) computer as OBDII diagnostic trouble codes.

common diagnostic trouble codes (DTC)
Diagnostic codes often associated with OBDII emission test failures. OBDII diagnostic codes from bad catalytic converters are pretty high on the list, but diagnostic codes related to other systems may rank even higher. In particular, OBD diagnostic codes are common for problems with the evaporative emission system (EVAP), engine misfiring, and lean fuel mixture. Oxygen sensor system and exhaust gas recirculation OBD codes are also possible.

diagnostic
An on-board diagnostic car computer, or OBD. The on-board diagnostic computer turns on your Check Engine Light and sets diagnostic trouble codes for fixing problems with your car's emission system.

Also known as: diagnostics, auto diagnostic, OBD

diagnostic code reader
The most basic auto diagnostic tool. The OBD diagnostic code reader is a less expensive tool with limited function that will read diagnostic trouble codes from your car's OBD computer.

Also known as: diagnostic tool, auto diagnostic code reader, OBD diagnostic tool

diagnostic scan tool
The more advanced OBD diagnostic tool. The OBD diagnostic scan tool may cost several hundred dollars, and will give the user more information regarding the diagnostic trouble codes than will the simpler diagnostic code reader.

Also known as: diagnostic tool, auto diagnostic scan tool, OBD diagnostic scan tool

diagnostic tools
Tools for scanning the car's OBD computer, or PCM, for auto diagnostic trouble codes and related information. Auto diagnostic tools include the more basic OBD diagnostic code reader, and the more advanced OBD diagnostic scan tool.

Also known as: OBD diagnostic tools, OBD diagnostics

diagnostic trouble codes (DTC)
Basic auto diagnostics information from your car's on-board diagnostic (OBD) computer, or PCM. OBDII diagnostic trouble codes are five-digit codes specifying problems related to smog control.  For example, OBD diagnostic codes related to your car's powertrain run between P0100 and P1899, and codes related to the auto body or auto chassis start with 'B' and 'C' respectively. The third digit of the OBD code specifies the major area of problem; for example '1' points to a problem with fuel or air, and '2' to the injector circuit. OBD diagnostic trouble codes come in two major types: generic diagnostic codes, and enhanced diagnostic codes (OEM diagnostic codes). It's important to realize that by itself, the diagnostic trouble code (DTC) does NOT tell you exactly what needs to be done: determining why the diagnostic code is there or the exact cause of the failure may be harder.

Also known as: diagnostic codes, auto diagnostic codes, OBD codes, OBDII codes

enhanced diagnostic trouble codes
OBD diagnostic codes that are specific to a particular car manufacturer, as opposed to generic diagnostic codes which apply to all automotive makes. Enhanced OBD diagnostic codes are also known as OEM (original equipment manufacturer) diagnostic codes, and cover nonemission diagnostic problems.

Also known as: enhanced OBD diagnostic codes, OEM OBD diagnostic codes

evaporative emission control system (EVAP) failure
One of the most common reasons for OBD diagnostic trouble codes and emission test failures, perhaps accounting for nearly 25%. The EVAP system keeps raw gas vapors from getting into the air. The most common reason for one OBD EVAP diagnostic code is having a loose fuel tank cap (gas cap) or a missing gas cap. Other EVAP problems that result in OBD EVAP diagnostic codes are broken or loose gas tank hoses, or a leaky charcoal cannister for capturing gas vapors.

Also known as: diagnostic code, OBDII diagnostic code, OBD2 diagnostic code

exhaust gas recirculation system (EGR) failure
A source of OBDII diagnostic codes and emission failures. The EGR sends exhaust back to the intake manifold for the purpose of lowering NOX air pollution.

Also known as: diagnostic code, OBDII diagnostic code, OBD2 diagnostic code

generic diagnostic trouble codes
OBD generic diagnostic codes are those that cover all automotive makes, rather than being specific to a particular make; diagnostic codes specific to a make are known instead as enhanced OBD diagnostic codes or OEM codes.

Also known as: generic OBD diagnostic codes, generic diagnostic code

malfunction indicator lamp
The warning light that comes on as a result of emission problems recorded as OBD diagnostic trouble codes. When the Malfunction Indicator Lamp comes on, which you see as the Check Engine Light, you have emission trouble, with OBDII diagnostic trouble codes recorded in your car's on-board diagnostic computer (OBD).

OBD (on-board diagnostic)
The diagnostic trouble codes in your on-board diagnostic (OBD) vehicle computer. The OBD diagnostic codes are primarily for identifying emission problems, but there are some nonemission OBD diagnostic codes as well.

Also known as: diagnostic, auto diagnostic, OBDII, OBD2, OBD II, OBD 2

OBDII (on-board diagnostic)
The current standardized version of diagnostic trouble code information for emission problems and some nonemission issues. Beginning in 1994 and especially in 1996, OBDII replaced the earlier OBD system on newly manufactured cars.

Also known as: diagnostic, auto diagnostic, OBDII, OBD2, OBD II, OBD 2

powertrain contol module (PCM)
The car's on-board diagnostic computer or OBD. The PCM turns on the Check Engine Light and generates OBD diagnostic codes in response to auto emission problems.

Also known as: OBD computer

Q: Why choose a Diamond Certified auto diagnostics shop?
A: Diamond Certified ends the guessing game by offering the auto diagnostics customer a choice of top-rated shop's who pass the most in-depth rating process. Most companies can’t pass such a high standard, which means only local auto diagnostics shops rated Highest in Quality earn the Diamond Certified award. American Ratings Corporation also looks at every Diamond Certified company with in-depth and ongoing research and ratings. And your auto diagnostics service purchase is always backed up by the Diamond Certified Performance Guarantee. So you're able to feel confident about having chosen a Diamond Certified auto diagnostics shop for your needs.

Q: What are my rights as an auto diagnostics customer in Alameda County?
A: Since 1974, the Automotive Repair Act has ensured your right to an estimate in advance on automotive diagnostic work, and to a list of charges when the OBD diagnostic service and associated repair or replacement work if any is finished. More information on your rights can be found at the California Bureau of Automotive Repair (BAR) (http://www.autorepair.ca.gov/).

Q: What are auto diagnostics?
A: Auto diagnostics may be thought of as on-board diagnostics (OBD), the on-board computer in your car that records a diagnostic trouble code indicating an emission problem (or maybe a nonemission problem) and turns on your Check Engine Light.

Q: What is the benefit of OBD (on-board diagnostics)?
A: On-board diagnostics (OBD) is a combination of sensors and computer hardware and software that checks cars for emission problems. Cars made in about 1988 began having OBD (on-board diagnostics) which became known as OBDI. Beginning with the manufacture of cars in 1994 and especially 1996, the original on-board diagnostics sytem was replaced in new cars by OBDII, also known as OBD2. OBDII turns on your car's malfunction indicator, or Check Engine Light, in response to smog control issues. OBDII can spot minor problems with the car and may prevent them from causing big repair expenses. OBDII may also detect problems that are causing extra gas costs.

Q: Why is my OBD Check Engine Light on?
A: In essence, it's on because your on-board diagnostic (OBD) computer has detected that you have an OBDII emission problem that may make your vehicle's smog production go 50% over the federal limit, even if the problem is not causing any driving problems that you can detect or causing other warning lights to come on.

Q: What is OBDII?
A: OBDII, variously known as OBD2, OBD II, and OBD 2, means the second version of on-board auto diagnostics. OBDII is the version of OBD found in all automobiles since at least 1996. OBDII replaced OBDI to bring standardization to OBD emission control, and to expand OBD emission control.

Q: So why exactly is OBDII turning on my Check Engine Light?
A: OBDII is constantly checking different smog-related diagnostic information. OBDII looks at your catalytic converter, your fuel mixture, the firing of your engine, and emission control systems like the evaporative emissions system (EVAP) and the exhaust gas recycling system (EGR). OBDII is watching everything that can affect emissions, and sending out diagnostic trouble codes (DTC) to the computer, detecting even a loose or missing gas cap.

Q: Is it safe to drive my vehicle with the OBD Check Engine Light on?
A: The Check Engine Light is largely about OBDII diagnostic information for smog control purposes. The Check Engine Light OBDII diagnostic is glaringly nonspecific: you don't know if you have a serious auto problem or not until a diagnostic scan is done and a systematic diagnostic evaluation is carried out to follow up the OBD diagnostic trouble code (DTC) discovered. You may not be able to tell that your car is driving any differently. You should always keep track of unusual signs like diagnostic noises, and should certainly be very aware of any other warning lights coming on that could be diagnostic for problems like oil or temperature trouble. But the Check Engine Light by itself may not indicate a drivability problem. It may be an OBDII problem as minor as not having had your gas cap twisted tightly enough (make sure you hear the gas cap click five times when you retighten it). The Check Engine Light does indicate an OBDII diagnostic smog control problem of some sort however, and eventually you will need to deal with it on your own or through a technician you can trust.

Q: How much does it cost to have my OBDII diagnostic trouble code (DTC) read?
A: Good news: some auto parts stores may do diagnostic scanning for free. It's certainly worth checking, and beats paying $90 or more at a dealership to be told to be sure you tighten your gas cap.

Q: What does it mean when my OBD Check Engine Light comes on?
A: It means your OBD (on-board diagnostic) computer system has detected a problem of some sort that could increase air pollution to increase, use extra gas, or cause engine trouble. Examples of OBD problems that waste gas and harm the environment are missing or loose fuel caps. An example of an OBD problem that could cause engine damage is a misfiring engine.

Q: What does it mean if my OBD Check Engine Light goes off?
A: It means that your OBD (on-board diagnostic) computer system has confirmed that the emission trouble causing the OBDII diagnostic trouble code, maybe an untighted fuel cap or a spark plug fouling, has been fixed. You don't need to worry further about a diagnostic emissions problem unless the OBD warning comes back on.

Q: What does it mean when my OBD Check Engine Light stays on?
A: It means your OBD (on-board diagnostic) computer system is warning you to find out if something is wrong fairly soon. When you stop, see if your gas cap is tightened down; a loose cap or a missing one can make your auto diagnostic system light come on. Remember when you get gas to always be sure your engine is not running, and to make sure your key is in the off position; not doing these things can turn on the OBDII diagnostic light. If the OBD Check Engine Light stays on after more trips, make plans to find out what the problem is using a diagnostic tool, or find a qualified diagnostic technician to get to the bottom of the problem.

Q: What does it mean when my OBD Check Engine Light flashes on and off?
A: A blinking OBD Check Engine Light is cause for concern. Your OBDII diagnostic system has spotted a severe problem, such as misfiring that could damage your catalytic converter. You can probably still drive the car without serious trouble, but you should not use it as much as otherwise, and should not use it at high speeds or with heavy loads until you can have the OBDII diagnostic trouble code taken care of.

Q: What will the OBDII technician do to take care of the OBD Check Engine Light problem?
A: The auto diagnostics technician will connect a scan tool to your vehicle's OBD computer memory. The scan tool will pull OBDII diagnostic trouble codes and related diagnostic information that the technician can use for the full diagnostic process necessary to pinpoint the exact trouble with your car.

Q: Will repair for the OBDII diagnostic trouble code be covered by the warranty on my car?
A: It very well might be. Warranties vary with the auto part that has caused the OBDII diagnostic failure and with the make of the car. Keep in mind that responding quickly to the OBD diagnostic failure may lower your cost. The Clean Air Act requires a warranty of 8 years or 80,000 miles on big emissions control parts like the catalytic converter, which may cause OBD failures, and requires warranties of 2 years or 24,000 miles on smaller items.

Q: What's the best way to find a good auto diagnostics shop or technician?
A: Remember the quality that Diamond Certified auto diagnostics shops offer.  Diamond Certified auto diagnostics shops offer value that may be unmatched by other locations. Diamond Certified shops have certified technicians, many prequalifications, numerous random consumer references, and a great guarantee.