Error Code P050E is defined as Cold Start Engine Exhaust Temperature Too Low. This is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, especially those made since 1996 up to present. It’s typically common among but not limited to Dodge, Ford (Escape, EcoBoost, Mustang, etc.), Jeep, Land Rover, Nissan, and Volkswagen. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.

When this code is stored, that means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has detected an exhaust temperature that is lower than the minimum threshold at cold start. The ‘Cold Start’ is a term used engine drivability implemented only when the engine is at (or lower) than ambient temperature. Thus, this code is common in places with extremely cold climates.

Exhaust temperature is only monitored on vehicles with clean-burning diesel propulsion system.

Exhaust temperature chance is important for emission reduction in clean-burning diesel engines. The PCM monitors the temperature to ensure that this takes place. DEF (Diesel Exhaust Fluid) injection systems are responsible for the introduction of the DEF into the catalytic converter and other areas of the exhaust system. DEF mixtures start the increase of exhaust temperature required to burn harmful hydrocarbons and nitrogen dioxide particles trapped within the exhaust system. The PCM controls this system.

During cold start, the exhaust temperature must be at or near the ambient temperature. If the PCM detects that it’s lower, then the Error Code P059E will be stored and the Check Engine light will be activated. In many cases, it takes multiple failures for the Check Engine light to light up.

Common Symptoms

  • Excess black smoke from the exhaust
  • Diminished engine performance
  • Increase in fuel consumption

In some cases, the code could be accompanied by other DEF related codes.

Possible Causes

  • Burnt or damaged exhaust temperature sensor wiring
  • Defective exhaust temperature sensor
  • Moisture trapped inside the exhaust that has been frozen
  • PCM programming error or bad PCM

How to Check

Diagnosis for this code should start with searching through the TSB (technical service bulletin) to find its corresponding diagnosis and repair based on definition and symptoms. Chances are, the manufacturer has provided a detailed procedure to fix this problem more accurately.

You will need a diagnostic scanner, DVOM (digital volt/ohmmeter), infrared thermometer with laser pointer, and a source for vehicle information. The latter will provide the diagnostic flow chart of this error code, connector face views and connector pin-out charts, wiring diagrams, and component testing procedure/specifications.

Next, check the connectors and wirings of the exhaust temperature sensor (focus more on wiring routed near high-temperature area). Connect the diagnostic scanner to the vehicle’s diagnostic port to retrieve all the stored codes and their pertinent data. Take note of this information, clear the codes, then take the vehicle for a test drive (at cold start) to see if the code comes back. The test drive will also displace moisture that may have been previously trapped in the exhaust system.

Use the DVOM to test the exhaust temperature sensor:

  • Set the DVOM at ohms
  • Disconnect the wiring harness of the sensor
  • Test the sensors using the specifications and procedures set by the manufacturer
  • If the sensor doesn’t comply with the manufacturer’s specs, then it must be replaced

If the exhaust temperature sensor is good, then the next step is to test the reference voltage and ground at the exhaust temperature sensor:

  • With KOEO (key on and the engine off), get access to the connectors of the exhaust temperature sensor
  • Put the DVOM on the right voltage setting (reference voltage is typically 5-volts)
  • Next, check the exhaust temperature connector’s reference pin with the positive test lead of the DVOM
  • Probe the ground pin of the same connector with the negative test lead of the DVOM
  • The DVOM should indicate a 5-volt reference (+/- 10-percent)

If you have determined reference voltage:

  • Observe exhaust temperature using the scanner’s data stream
  • Compare the exhaust temperature displayed on the scanner to the actual temperature that you detected using the infrared thermometer
  • If the two temperature differ by more than the maximum allowable threshold, then that means the exhaust temperature sensor has failed
  • If the two are within specifications, suspect a PCM malfunction or a programming error

If the reference voltage is not discovered:

  • Determine whether you have a voltage problem or ground problem by connecting the DVOM’s negative test lead to battery ground, and positive test lead still probing the reference voltage of the same connector, all while at KOEO
  • A voltage problem will need to be traced back to the PCM
  • A ground problem will need to be traced back to the appropriate ground junction
  • The exhaust temperature sensor is frequently confused with an O2 (oxygen) sensor
  • Be extra careful when working around a hot exhaust

How to Fix

Depending on your diagnosis, common repairs for this code would be:

  • Replacement of exhaust temperature sensor
  • Repair or replacement of burnt or damaged exhaust temperature sensor wiring
  • Replace or reprogram PCM

When Error Code P050E is stored, that means the DEF injection is likely to be disabled. Thus, it must be addressed as soon as possible.