Q: check engine light on with code P0139 and P0841. Added Techron last fill up and now light went off, on and off again. What is go

asked by on May 08, 2017

check engine light on with code P0139 and P0841. Added Techron during last fill up about 5 days ago and now light went off after driven 30 miles, but it came back on again with another 20 miles. The light went off again this morning after another 40 miles driven. What is going on?

My car has 50000 miles.
My car has an automatic transmission.

The trouble codes that you have downloaded have not arisen due to the use, or non-use, of the fuel additive. Code P0841 simply refers to an abnormality in the transmission fluid pressure sensor circuit. Possible causes of that code include a faulty electronic pressure control solenoid, a defective transmission fluid pressure sensor, blockages inside the internal transmission fluid passages, low transmission fluid or dirty and contaminated transmission fluid and, finally, internal mechanical transmission failure.


The other code, namely P0139 will set if the O2 sensor for bank 1 (sensor 2 on bank 1) fails to report a voltage below .2 volts for 7 seconds during a deceleration fuel cut off. The oxygen sensor itself could be faulty and/or there could be excessive fuel still in the exhaust stream from possible leaking in the fuel injection system.


Both of these codes would have occurred whether you used the fuel system cleaner or not. The reason the codes are appearing intermittently is simply because the failure itself is "intermittent". If you were to wait long enough, whatever component is causing the failure will completely fail and then the engine light will stay on constantly. If you desire a diagnostic covering both codes, performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a check engine light diagnostic and the responding certified mechanic will diagnose the issue(s) and let you know of the required repairs and the cost. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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

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

How to install A/C blower? 2008 Mazda 5

Hi there: If you've never completed this type of job, I highly recommend having a professional mechanic replace your AC blower motor; as there are multiple electrical components, relays and other parts that can be damaged due to improper removal...

Overheating

If the engine overheats in the first 5 to 7 minutes of running then you most likely have a water pump that is not circulating fluid or the thermostat is stuck in the closed position. You should start and run...

All lights are working except my tail lights. What's the problem?

The front and rear parking lights are on the same circuit, so first, check to see if the front parking lights are working. If the parking lights are not working with the headlight switch in the on position, then locate...

Related articles

P0258 OBD-II Trouble Code: Injection Pump Fuel Metering Control “B” Low (Cam/Rotor/Injector)
P0258 P0258 code definition Injection Pump Fuel Metering Control “B” Low (Cam/Rotor/Injector) What the P0258 code means P0258 is an OBD-II generic code for the injection pump fuel metering control valve circuit having low or no current flow when the...
P0248 OBD-II Trouble Code: Turbocharger Wastegate Solenoid B Range/Performance
P0248 code means the solenoid is not controlling wastegate activity in the intended manner due to a faulty solenoid, wiring, or a stuck wastegate door
P2195 OBD-II Trouble Code: O2 Sensor Signal Stuck Lean Bank 1 Sensor 1
P2195 trouble code definition O2 Sensor Signal Stuck Lean Bank 1 Sensor 1 What the P2195 code means P2195 is an OBD-II...