Q: My car shows a P0420 code and the engine coolant temperature reading (via torque pro app and elm327 Bluetooth reader) stayed at 84.2 degrees

asked by on

How low can the ect read, I'm pretty sure a faulty ect is my issue that or an o2 sensor, because the cataylist should still be fine with the mileage on this car, but I have not ruled it out completely, car was parked for roughly 5 hrs before checking then I first done KOE to get code, cleared and monitored PIDs with engine running approximately 5 min (I feel the owner of the car has been swindled by a shop) Thanks

My car has 90000 miles.
My car has an automatic transmission.

Hi there - "boundary measured engine temperature," or the lowest temp reading a sensor can transmit, can be different based on each temperature sensor. The issue here is what is the true engine temperature? Is the thermostat getting the engine up to its design temperature (something near 205 degrees Fahrenheit/100 Centigrade). Can you cross-check the engine temperature with a laser thermometer, cockpit temperature gauge (middle of the gauge usually), or other measuring device? If the engine is truly coming up to 200 degrees (F) or so, then yes, the ECT can read "low" to the computer, causing rich mixture running. This could cause a low catalytic converter efficiency problem if the engine has run rich for a while.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My car shows a P0420 code and the engine coolant temperature reading (via torque pro app and elm327 Bluetooth reader) stayed at 84.2 degrees

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Tire going flat despite no visible damage

Hi, it can be very hard to find holes in a tire sometimes as they can be very small. It is also possible that the Schrader valve on the tire is damaged and leaking air slowly. You can try putting...

Q: Q: water is leaking

If you are getting a coolant leak behind a manifold then you may have a coolant pipe, hose leak on the intake side of engine or a head gasket or freeze plug leak on the exhaust side of engine. Have...

Q: After sensor replacement, 2nd diagnostic revealed P0139

No, it is not the catalyst. The P0139 code is for the O2 sensor before the catalyst. The code is illuminated when the engine control module is testing the O2 sensor and it cuts the fuel to see if the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...