Coolant temperature sensor

mazdasd

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Mazda CX-5 2014
I have a 2014 CX-5 Sport. My check engine light recently came on. My code scanner showed P011A Coolant temperature Sensors 1/2. I went ahead and replaced the sensor. About 2 weeks later the check engine light came back on and my scanner shows the same code. After some searching I figured it might be the coolant thermostat. I picked up a new one for about $10 at autozone and replaced that. I have reset the check engine light and am hoping it doesn't come back on in a week or so. But I just found out that there are two ECT's on this car. The one I replaced is right by the housing for the thermostat. Where is the other one located and is it the exact same piece as the other sensor? If it helps, I have found that most of the parts for the 2014 CX-5 are the same as the 2013 model.
 
Are you still under warranty? If you are, why not let Mazda diagnose and repair this. Your situation is a classic example of the misuse of diagnostic codes by shade tree mechanics. The code will usually point you in the general direction of the problem, but the next step is to determine exactly what component is causing the malfunction which is beyond what any code scanner can do.
 
Bumper to bumper warranty is past. I confirmed with the dealership that this isn't under the power train warranty. I don't want to take it to the shop when I can fix it myself for pennies to the dollar of what they would charge. I'm reading through the service manual right now. Thanks.
 
I figured I'd update my progress. The check engine light came back on the morning after replacing the thermostat. It appeared about 15 minutes into a 30 minute drive. The second ECT sensor was easy enough to find. For any who might have this issue themselves, here's where they both are: Coolant temperature sensor 1 is located on the engine slightly above the housing for the thermostat (Next to the battery). You will need a deep 3/4 inch (19 mm) socket. The 2nd ECT sensor is located on the passenger side against the firewall. there are 2 hoses gong into a metal connection. The sensor is on top with the wire plug going into it. Should be obvious but disconnect the plug before unscrewing the sensor to prevent damaging the wires. I picked up the sensor from AutoZone for $30. I replaced the sensor last night in about 10 minutes. I did not have to drain any coolant to replace the sensors. However, if you replace the Thermostat you do need to drain some into a clean container so you can pour it back in when you are done. The service manual for the CX-5 has fairly detailed instructions to replace the thermostat. The main thing is to disconnect the negative battery terminal first, and remove the battery. Trust me when I say it is a pain to remove the thermostat housing if you do not remove the battery. I think it also says to disconnect the air hose, but that wasn't really in my way. It may help you elevate the hose to keep from losing coolant though. So in total I spent $70 on parts because I threw out the first sensor after removing i because i thought it was bad. I already had the tools. Even though I ended up spending more than I needed to It was still about half the price of taking it to the shop for them to do. The car drove about 30 minutes this morning without the light coming back on. If it ends up coming back on I will take it to the shop to get it done. You might have to use a code scanner to erase the fault code and get the engine light to turn off. However, The service manual has you disconnect the battery before doing any of these steps which by itself might reset you cars computer and erase the light. Hope this helps anyone else that has this issue.
 
Yea, if I can try a $30 worth of parts that might address the issue, I'd rather before the dealer charges $100 or more simply to diagnose.
There's actually a guy on the cx-5 FB page getting a new motor because the dealership tech did not refill oil into the engine after draining..
 
OK so after a day the light came back on. But I have noticed a new Symptom. the weather just recently started getting cooler so in the morning we had to turn the heat on. It usually takes a bit for the heater to start blowing hot. However, even after a 30 minute drive there is no heat coming from the vents. The vents are blowing nice an strong and each setting works. The engine temp indicator never shows it is overheating and the cold indicator goes off after the usual time. (Why didn't they put an actual gauge for the Engine Temp?) Anyway, I am going to check on the easy stuff first according to what I found online. First, is to let the car run for awhile to get to normal temp. I will check the water hoses that go through the fire wall. If they are both hot then the coolant flow can be ruled out as the problem. If one of them isn't hot then your close to the problem. I'll check the heater control valve to make sure its working correctly. Some cars have a mechanical valve, some electric, and some may not have one at all. If the valve is fine then It might be a clog in the heater core. There are cheap kits available to flush your heater core and instructional videos as well. If those don't seem to be the issue, ill probably end up taking it to the shop to just get it over with and move on. Ill update this again once the problem is finally solved. FYI this car is barely over 2 years old and I'm having this issue. I have a 2006 Toyota corolla that's about to be 10 years old and the only issue is the passenger airbag recall they recently had which they're replacing for free. My next car will not be a mazda.
 
So you're spending all this time and money replacing parts with stuff sourced from Autozone (non OE) and you figure this is better than a trip to the dealer?
 
OK so after a day the light came back on. But I have noticed a new Symptom. the weather just recently started getting cooler so in the morning we had to turn the heat on. It usually takes a bit for the heater to start blowing hot. However, even after a 30 minute drive there is no heat coming from the vents. The vents are blowing nice an strong and each setting works. The engine temp indicator never shows it is overheating and the cold indicator goes off after the usual time. (Why didn't they put an actual gauge for the Engine Temp?) Anyway, I am going to check on the easy stuff first according to what I found online. First, is to let the car run for awhile to get to normal temp. I will check the water hoses that go through the fire wall. If they are both hot then the coolant flow can be ruled out as the problem. If one of them isn't hot then your close to the problem. I'll check the heater control valve to make sure its working correctly. Some cars have a mechanical valve, some electric, and some may not have one at all. If the valve is fine then It might be a clog in the heater core. There are cheap kits available to flush your heater core and instructional videos as well. If those don't seem to be the issue, ill probably end up taking it to the shop to just get it over with and move on. Ill update this again once the problem is finally solved. FYI this car is barely over 2 years old and I'm having this issue. I have a 2006 Toyota corolla that's about to be 10 years old and the only issue is the passenger airbag recall they recently had which they're replacing for free. My next car will not be a mazda.

You never mentioned how your old sensors tested out?

A stuck open thermostat will cause the temp sensors to throw a code, and a stuck open thermostat will cause the heater not to get hot enough.

My money is on the thermostat being faulty.

However here is some info in the p011a code relating to a block heater if you have a block heater. http://oemdtc.com/19165/check-engine-light-on-with-dtc-p0116-or-p011a-when-starting-in-cold-weather-2012-2016-mazda-vehicles
 
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You never mentioned how your old sensors tested out?

A stuck open thermostat will cause the temp sensors to throw a code, and a stuck open thermostat will cause the heater not to get hot enough.

My money is on the thermostat being faulty.

However here is some info in the p011a code relating to a block heater if you have a block heater. http://oemdtc.com/19165/check-engine-light-on-with-dtc-p0116-or-p011a-when-starting-in-cold-weather-2012-2016-mazda-vehicles

A faulty thermostat will not throw this code.
This code simply means that one of the two sensors is reading WAY too high, or way too low.
The most likely cause is a loose or corroded connector.
 
As far as money, the things I have replaced are cheaper than one trip to the shop. The dealer overcharges, and just because a part has Mazda's name on it, doesn't mean its better than what you get at a parts store. It might take longer for me to figure out what the problem is, but i prefer to figure out and know I'm not being ripped off by the dealer.
 
I'm thinking the connectors might be faulty. Kind of annoying since the cars barely 2 years old and everything is maintained. I will be checking them with the this weekend along with the other stuff. I went ahead and replace the thermostat already since its only $10.
 
A faulty thermostat will not throw this code.
This code simply means that one of the two sensors is reading WAY too high, or way too low.
The most likely cause is a loose or corroded connector.

Ok, that makes sense. So the computer is detecting an out of range due to extra resistance in the circuit due to corrosion at the ect connector, or at what other possible junctions or connectors before the signal reaches the ECU?

Perhaps the same electrical junction is also affecting the heater valve?
 
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Why wouldn't be this be covered under powertrain?

because the powertrain warranty only covers specific parts.
http://www.mazdausa.com/MusaWeb/displayPage.action?pageParameter=legalTermsPowertrain

Powertrain Warranty Parts List
The listed below are the powertrain components covered under the Powertrain Limited Warranty:
Engine
Cylinder Block, Cylinder Head, and All Internal Lubricated Parts (Piston engines)
Rotor Housing and All Internal Parts (Rotary engines)
Timing gears
Timing chain/belt and tensioner
Timing chain/belt front cover and gaskets
Flywheel
Valve Covers
Oil Pan
Oil Pump
Intake Manifold
Exhaust Manifold
Engine Mounts
Turbocharger Housing and All Internal Lubricated Parts
Supercharger Housing and All Internal Lubricated Parts
Powertrain Control Module
Water Pump and Gasket
Thermostat
Fuel Pump
Seals and Gaskets
Freeze Plugs were not added
Transmission and Transaxle
Transmission Case and All Internal Parts
Torque converter
Clutch Pressure Plate
Transmission Mounts
Transfer Case and All Internal Parts
Transmission/Transaxle Control Module
Front/Rear Drive System
Final Drive Housing & all Internally Lubricated Parts
Manual and Automatic Hub (4X4)
Front Wheel Hubs and Bearings (FWD Transaxles)
Rear Axle Housing & all Internally Lubricated Parts
Axle/Drive Shafts
Propeller shaft (RWD and AWD only)
Universal Joints
Constant Velocity Joints
Rear Axle/Hub Bearings (RWD and AWD only)
Seals and Gaskets
 
I'm not gonna go out and buy an extended warranty because I feel the CX-5 is going to be reliable in the long haul but basic powertrain warranty does seem somewhat weak. I can understand things like an AC exclusion but all sensors that ensure the engine is running properly should be included. Heck... it should be under the Federal Emission warranty if nothing else since the engine's knowledge of temps could affect emissions.

EDIT: I guess not on Federal

Emission Control Parts
1. Exhaust Gas Conversion Systems: oxygen sensor, thermal reactor, catalytic converter,
dual-walled exhaust pipe
2. Exhaust Gas Recirculation System: EGR valve, thermal vacuum switch, EGR solenoid,
EGR spacer plate, EGR backpressure transducer, sensor and switches use to control EGR
flow
3. Evaporative Emission Control System: purge valve, fuel filler cap, purge solenoid, vapor
storage canister and filter
4. Positive Crankcase Ventilation (PCV) System: PCV valve, PCV solenoid
5. Air Injection System: Air pump, diverter, bypass, or gulp valve, reed valve, anti-backfire
or deceleration valve
6. Early Fuel Evaporative (EFE) System: EFE valve, thermal vacuum switch, heat riser
valve
7. Fuel Metering System: electronic control module (unit) or EFI air flow meter, computer
command module or mixture control unit, deceleration controls, electronic choke, fuel
injectors, fuel injection units and fuel altitude compensator sensor, bars or rails for EFI
or TBI systems, mixture settings on sealed fuel mixture control solenoid, diaphragm or
other systems, fuel metering components that achieve closed/other feedback control sen
sors/loop operation switches and valves
8. Air Induction System: thermostatically controlled air cleaner, air box
9. Ignition Systems: electronic spark advance timing advance/retard systems, high energy
electronic ignition
10.Miscellaneous Parts: hoses, gaskets, brackets, clamps and other accessories used in the
above systems
Emission Related Parts
These are examples of other parts of your vehicle which have a primary purpose other than
emissions control but which nevertheless have significant effects on your vehicle’s emissions. If
any of these parts fail to function or function improperly, your vehicle’s emissions may exceed
federal standards.


Therefore, when any of the parts of the following systems are defective in materials or workmanship and have failed in a way that would be likely to cause your vehicle’s
emissions to exceed federal standards, they should be repaired or replaced under the emissions
warranty:
1. Fuel Injection System: fuel distributor
2. Air Induction System: turbocharger, intake manifold
3. Exhaust System: exhaust manifold
4. Ignition System: distributor, spark plugs, ignition wires and coil
5. Miscellaneous Parts: hoses, gaskets, brackets, clamps, and other accessories used in the
above systems.
 
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Comes from the former owner of the auto shop. Never ever use aftermarket thermostats. Applies to few more things, but the the thermostats are the worst.
 
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