Showing articles & questions for topic
diagnostics

The electronic control unit (ECU) used in today’s cars and trucks is used to control the engine and other components’ functions. An ECU is a computer with internal pre-programmed and programmable computer chips that is not much different from a...

If Diagnostic Trouble Codes were downloaded, those codes would really would be key to advising you. If there is no spark, obviously all ignition system components are possible suspects but if the coil(s) and spark plugs are new, the crankshaft...

Hello, thank you for writing in. The components you have checked thus far have been valid steps. You want to go through system by system, and make sure the engine is getting what it needs. Start with the fuel system,...

If your vehicle's check engine light (https://www.yourmechanic.com/article/what-does-the-check-engine-warning-light-mean-by-spencer-cates) illuminates, there is a malfunction that should be diagnosed and repaired. If the check engine light is flashing, that means there is a serious fault, such as cylinder misfiring, that requires immediate repair....

There are innumerable things that can go wrong with the A/C system and so the best thing to do is request an air conditioning system inspection (https://www.yourmechanic.com/services/ac-is-not-working-inspection) and the responding certified mechanic will get this resolved for you. The possibilities...

The purpose of the SES light is to alert you that there is a malfunction in the engine or powertrain. When the SES light turns on, you can attach a code scanner to the vehicle's OBD-II port under the steering...

If code P0136 (https://www.yourmechanic.com/article/p0136-obd-ii-trouble-code-o2-sensor-circuit-malfunction-bank-1-sensor-2-by-jay-safford) sets the only way you can determine if the oxygen sensor has failed is to use an automotive scope to graphically depict the sensor output waveform (it will look roughly like a sine wave) and switching...

If you call out a mechanic to install a part that was diagnosed by another company then to answer your question is no. The mechanic that is to install a previously diagnosed parts cannot in most cases verify the part...

The diagnostic service fees are not included in the service call. If a diagnosis is needed to find out the problem then the mechanic needs to be compensated for their time to do the diagnosis service.

The cause behind diagnostic trouble code P0171 (https://www.yourmechanic.com/article/p0171-obd-ii-trouble-code-system-too-lean-bank-1-by-andrew-quinn) is easiest to find by looking at the secondary firing patterns on the Bank one cylinders. That will confirm if the too lean condition, that has caused the code to set, affects...

The battery should be load tested by a professional. Load testing can only be reliably performed on a fully charged battery. If the battery passes a load test be sure it is NOT a marginal pass in which case you...

I would call YourMechanic to come and diagnose this problem.

The cause behind diagnostic trouble code P0171 (https://www.yourmechanic.com/article/p0171-obd-ii-trouble-code-system-too-lean-bank-1-by-andrew-quinn) is easiest to find by looking at the secondary firing patterns on the Bank one cylinders. That will confirm if the too lean condition, that has caused the code to set, affects...

If the ABS warning light is on, that means that there are downloadable ABS diagnostic trouble codes, much like the codes you would download if you have a Check Engine Light diagnostic (https://www.yourmechanic.com/services/check-engine-light-is-on-inspection). The ABS trouble codes will give a...

Trouble code P1705 implicates the throttle position sensor (TPS). A transmission fault (which is indicated by a flashing "D4") can arise if the TPS is malfunctioning. Consequently, I would recommend testing the TPS first. Once code P1705 is resolved, then...

Check to see if any diagnostic trouble codes have been stored in both the PCM and TCM. Check the fuses in the circuits that power the transmission controls. Occasionally, a short in a sensor such as an oxygen sensor will...

Nothing should be replaced until you have in hand a definitive diagnostic pinpointing the faulty segment of the car's electrical system. There may be too much voltage drop in the charging circuit, as well as elsewhere, but start with the...

Code U1100 signifies a communications error which is either a module fault or a deficiency in the wiring harness between communicating modules. There's a possibility that a dying battery is a cause of such a code (and a cause of...

If your vehicle's check engine light (https://www.yourmechanic.com/article/what-does-the-check-engine-warning-light-mean-by-spencer-cates) illuminates, there is a malfunction that should be diagnosed and repaired. If the check engine light is flashing, that means there is a serious fault, such as cylinder misfiring, that requires immediate repair....

PCM's are usually replaced at the end of a "process of elimination". That is, with most engine management control failures, there are a whole host of common causes that are evaluated first. Once that long list of most common causes...