car electric doctor

Updated: January 09, 2019 It's what almost every motorist has to go through once in a while: the Check Engine or Service Engine Soon light. If this warning light stays on, it means that your vehicle's computer has detected a problem that can affect your vehicle's fuel economy and emissions.  Check Engine or Malfunction indicator light (MIL) Let's explore your options on how to deal with it. First, shortly how it works. Your car has a computer (in the photo) that controls the powertrain (engine and transmission). This computer is called Powertrain Control Module (PCM). It works by monitoring signals from various sensors and adjusting the engine and transmission performance for better fuel economy and lower emissions. This computer has a self-testing capability (called ON-Board Diagnostic or OBD-II). When it detects a fault with one of the systems or sensors, it turns on the Check Engine light on your dash. At the same time, it stores the fault code in its me...

the optimum level, which is about 14.7:1. Air fuel ratio sensor problems Problems with air fuel ratio sensors are common. Often a sensor gets contaminated or simply fails. In some cars, the heating element inside the sensor fails causing the malfunction. For example, in many Toyota and Honda cars the code P0135 may be caused by a failed heating element inside the sensor. See how the heating element of the A/F sensor is checked in this article:  code P0135 . ADVERTISEMENT - CONTINUE READING BELOW In some cars, a sensor wiring may get shorted out after rubbing against metal parts. For example, in older Mazda 3, the sensor wire may rub against the bracket and short out causing the code P0131. When the engine computer detects that the air fuel ratio sensor signal is out of expected range it illuminates the check engine light. Most common OBDII trouble codes related to an air fuel ratio sensor are  P0131 ,  P0134 ,  P0135 , P0133, P0031 and P1135. Are there a...

00's oxygen sensors started to give way to more precise air fuel ratio sensors.  Air fuel (A/F) ratio sensor An air fuel ratio (A/F) sensor measures oxygen content of the exhaust in a wider range. Looking similar to a conventional oxygen sensor, the A/F sensor has more wires. It is also known as "broadband lambda sensor" or "lambda probe." The air fuel ratio sensor is installed in the exhaust manifold or in the front exhaust pipe, before the catalytic converter. The job of the air fuel ratio sensor is to measure the oxygen content in the exhaust and provide feedback to the engine computer (PCM). Based on air fuel ratio sensor signal, the computer adjusts the air to fuel ratio to keep it at the optimum level, which is about 14.7:1. Air fuel ratio sensor problems Problems with air fuel ratio sensors are common. Often a sensor gets contaminated or simply fails. In some cars, the heating element inside the sensor fails causing the malfunction. For exa...

00's oxygen sensors started to give way to more precise air fuel ratio sensors.  Air fuel (A/F) ratio sensor An air fuel ratio (A/F) sensor measures oxygen content of the exhaust in a wider range. Looking similar to a conventional oxygen sensor, the A/F sensor has more wires. It is also known as "broadband lambda sensor" or "lambda probe." The air fuel ratio sensor is installed in the exhaust manifold or in the front exhaust pipe, before the catalytic converter. The job of the air fuel ratio sensor is to measure the oxygen content in the exhaust and provide feedback to the engine computer (PCM). Based on air fuel ratio sensor signal, the computer adjusts the air to fuel ratio to keep it at the optimum level, which is about 14.7:1. Air fuel ratio sensor problems Problems with air fuel ratio sensors are common. Often a sensor gets contaminated or simply fails. In some cars, the heating element inside the sensor fails causing the malfunction. For exampl...

A failing sensor can cause intermittent problems: a car may cut out or stall randomly, but then restart with no problems. The engine might have troubles starting in wet weather, but starts OK after. Sometimes you might see the RPM gauge behaving erratically. In some cases, a failing sensor can cause long crank time before the engine starts. If the sensor is bad, the engine will crank but won't start. Read more:  Why an engine cranks but won't start: common problems . Crankshaft position sensor problems Crankshaft position sensor The most common OBDII code related to the crankshaft position sensor is  P0335 - Crankshaft Position Sensor "A" Circuit . In some cars (e.g. Mercedes-Benz, Nissan, Chevy, Hyundai, Kia) this code is often caused by a failed sensor itself, although there could be other reasons, such as wiring or connector issues, damaged reluctor ring, etc. In some cars, the intermittent stalling can also be caused by a problem with the crankshaft pos...

Ford Crankshaft position sensor (CKP) The crankshaft position sensor measures the rotation speed (RPMs) and the precise position of the engine crankshaft. Without a crankshaft position sensor the engine wouldn't start.  In some cars, the sensor is installed close to the main pulley (harmonic balancer) like in this Ford in the photo. In other cars, the sensor could be installed at the transmission bell housing, or in the engine cylinder block, as in the photo below. In the technical literature, the crankshaft position sensor is abbreviated to CKP. How the crankshaft position sensor works In this GM engine, the crankshaft position  sensor is installed at the cylinder block The crankshaft position sensor is positioned so that teeth on the reluctor ring attached to the crankshaft pass close to the sensor tip. The reluctor ring has one or more teeth missing to provide the engine computer (PCM) with the reference point to the crankshaft position. As the crankshaft ro...

How a starting system works: When you turn the ignition key to the START position, or press the START button, if the transmission is in Park or Neutral, the battery voltage goes through the starter control circuit and activates the starter solenoid. The starter solenoid powers the starter motor. At the same time, the starter solenoid pushes the starter gear forward to mesh it with the engine flywheel (flexplate in an automatic transmission). The flywheel is attached to the engine crankshaft. The starter motor spins, turning over the engine crankshaft allowing the engine to start. In cars with a push button start, the system disengages the starter as soon as the engine starts running. Neutral safety switch Automatic transmission range switch For safety reasons, the starter motor can only be operated when the automatic transmission is in Park or Neutral position; or if the car has a manual transmission, when the clutch pedal is depressed. In vehicles with a manual transmissi...

ADVERTISEMENT - CONTINUE READING BELOW Battery cables Starting system simplified diagram As we mentioned, the starter motor requires a very high electric current to turn over the engine, that's why it's connected to the battery with thick (large gauge) cables (see the diagram). The negative (ground) cable connects the negative " - " battery terminal to the engine cylinder block, or transmission, close to the starter. The positive cable connects the positive " + " battery terminal to the starter solenoid. Often, a poor connection at one of the battery cables can cause a starter motor not to run. How a starting system works: When you turn the ignition key to the START position, or press the START button, if the transmission is in Park or Neutral, the battery voltage goes through the starter control circuit and activates the starter solenoid. The starter solenoid powers the starter motor. At the same time, the starter solenoid pushes the starte...

A starter is an electric motor that turns over or "cranks" the engine to start it. It consists of a powerful DC (Direct Current) electric motor and the starter solenoid that is attached to the motor (see the picture). In most cars, a starter motor is attached to the transmission, see these photo 1  and  photo 2 .  Starter motor. Click for  larger photo The starter motor is powered by the car battery. To turn over the engine the starter motor requires a very high electric current, which means the battery has to have sufficient power. If the battery is discharged, the lights in a car might come on, but it won't be enough power (current) to turn over the starter motor. What are the symptoms of a bad starter motor: With the fully charged battery, when starting a car, nothing happens or there is a single click, but the starter motor doesn't run, even though there is a 12-Volt power at the starter control terminal. Another symptom is when the starter motor runs, ...