P2035 – Exhaust gas temperature (EGT) sensor 2, bank 2 – circuit low

Reinier

By Reinier (Contact Me)
Last Updated 2017-01-13
Automobile Repair Shop Owner

Trouble CodeFault LocationProbable Cause
P2035 Exhaust gas temperature (EGT) sensor 2, bank 2 - circuit low Wiring short to ground, EGT sensor

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What Does Code P2035 Mean?

OBD II fault code P2035 is a generic code that is defined by all manufacturers as “Exhaust gas Temperature (EGT) sensor 2, bank 2 – circuit low”, and is set when the PCM (Powertrain Control Module) detects a lower than expected signal voltage from the #2 EGT (Exhaust Gas Temperature) Sensor. This sensor is located downstream of the catalytic converter, although in some cases, it could be located close to, but downstream of, the turbocharger, or close to, but upstream the DPF (Diesel Particulate Filter) on diesel applications. On engines with two cylinder heads, “Bank 2” refers to the bank of cylinders that does not contain cylinder #1.

The sole purpose of Exhaust Gas Temperature sensors is to monitor the temperature of the exhaust gas to prevent damage to prevent catalytic converters from being damaged by excessively hot exhaust gas. Note though that on diesel applications, readings from this sensor is also used by the PCM to determine the correct moment to initiate the DPF (Diesel Particulate Filter) regeneration process.

On fully functional engines where there are no vacuum leaks, misfire codes, exhaust leaks, or issues with valve/camshaft or ignition timing present, the exhaust gas will always fall within a relatively narrow temperature range if that vehicle is operated normally. While changes in engine speed/load, throttle setting, injector pulse width, and ignition timing will produce changes in the exhaust gas temperature, these changes are normal, and more or less directly proportional to the changes in operating conditions.

However, some conditions/circumstances, such as using large throttle openings at low road speeds, while driving in the incorrect gear while towing heavy trailers, or towing trailers uphill, often combine to produce exhaust temperatures that exceed the maximum limit set by the applications’ manufacturer. While exceeding the maximum temperature limit for short periods will generally not harm the catalytic converter, operating the vehicle with elevated exhaust temperatures for extended periods will certainly damage the catalytic converter. Note that in this context, “extended periods” means no more than a few miles, or a few minutes at most.

NOTE: In extreme cases, such as where some types of misfires are present, or where the air/fuel mixture is abnormally rich, the catalytic converter can melt in as few as 10 to 12 seconds.

In terms of operation, EGT sensors are simple, temperature-reactive resistors (or sometimes, simple thermocouples) that react to changes in temperature in a predictable fashion. In practice, the sensor is supplied with a 5-volt reference voltage; as the temperature of the exhaust gas that flows over the sensing element increases, the sensors’ resistance decreases, which causes the feedback signal voltage sent to the PCM to increase. The opposite happens when the exhaust gas cools: as the gas cools, the resistance of the sensor increases, which in turn, causes the feedback signal voltage to decrease.

Thus, by constantly monitoring the temperature of the exhaust gas, the PCM is able to make suitable (and timely) adjustments to various engine management and fuel system parameters to control the exhaust gas’ temperature on a continual basis to prevent damage to the catalytic converter. However, the PCM does not merely monitor the temperature of the exhaust gas; the PCM is programmed to “know” what the temperature of the exhaust should be at any given moment to within a narrow margin, so if the signal voltage from the EGT sensor is lower than expected given the current operating conditions for a period of time set by the manufacturer, the PCM will set code P20135, and illuminate a warning light.

The image below shows the typical arrangement of exhaust Gas Temperature sensors on either side of a catalytic converter. The red arrow indicates the direction of gas flow through the system. Note though the actual location(s) of both upstream (EGT sensor #1), and downstream (EGT sensor #2), EGT sensors vary between applications. Always refer to the manual for the application being worked on to locate and identify EGT sensors correctly to avoid confusion and misdiagnoses when EGT sensors are confused with any of several other types of sensors that are common on modem exhaust systems today.

EGT 2

What are the common causes of code P2035?

Typical causes of code P2035 could include the following-

  • Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors
  • Defective Exhaust Gas Temperature sensor
  • Use of unauthorized, and often-illegal aftermarket exhaust systems/parts that decrease exhaust back pressure, which in turn, affects the temperature of the exhaust gas
  • Large exhaust leaks upstream of the EGT sensor can also decrease back pressure, and hence, the exhaust gas temperature
  • Failed or failing PCM. Note that this is a rare event, and the fault must be sought elsewhere before any controller is replaced

What are the symptoms of code P2035?

In most instances of P2035, the only symptom will be a stored trouble code and an illuminated warning light.

How do you troubleshoot code P2035?

SPECIAL NOTES: There are many reasons why the exhaust temperature can be elevated to above the maximum acceptable limit, and some of these causes could lead to fatal engine damage. For this reason, it is NOT a good idea to ignore this code simply because there are no discernible driveability issues or symptoms present. Long experience in the auto repair trade has taught that anything can happen at any time on any application, and if critical components like the EGT sensor(s) is/are out of commission, the first sign(s) of trouble might only become apparent when the engine seizes due to overheating, or the catalytic converter melts due to elevated exhaust gas temperatures caused by an overly rich air/fuel mixture. END OF SPECIAL NOTES. 

NOTE: Apart from a repair manual for the application being worked on and a good quality digital multimeter, having access to a laser-based thermometer and a heat gun will make diagnosing this code a lot easier.

Step 1

Record all fault codes present, as well as all available freeze frame data. This information can be of use should an intermittent fault be diagnosed later on.

NOTE: Be aware that many Air/Fuel Metering issues can either foul, and/or damage both oxygen -, and EGT sensors, which could result in code P2035 being set. Therefore, it is critically important that the entire OBD II system be scanned for all active and pending codes whenever code P2035 is encountered on any application, and furthermore that all Air/Fuel Metering related codes be resolved before attempting the diagnostic/repair procedure(s) for P2035.

Step 2

Assuming that there are no other codes present along with P2035, refer to the manual for the application to locate the relevant EGT sensor, as well as the location, function, routing, and color-coding of all associated wiring.

NOTE: Be careful not to confuse the EGT sensor with an oxygen sensor, since some applications have oxygen sensors located close to the turbocharger.

Step 3

Perform a thorough visual inspection of all associated wiring, and look for damaged, burnt, shorted, disconnected, or corroded wiring and connectors. Make repairs as required, clear the code, and rescan the system to see if the code returns.

Step 4

If no visible damage to the wiring is found, refer to the manual for details (KOER/KOEO) on how to establish the ground connection and reference voltage, disconnect the wiring from the sensor, and check both the ground and reference voltage circuits.

In most, if not all cases, the reference voltage will be 5 volts, and the will be ground supplied by the PCM.  If these values check out, proceed to test the resistance of the sensor itself. Refer to the manual to identify the correct pins to do this, and compare the obtained reading with the value stated in the manual. Replace the sensor if its resistance does not fall within the range specified by the manufacturer.

Step 5

If the reference voltage is less than 5 volts the connector, refer to the manual to determine the maximum allowable deviation, and if the difference exceed specifications, disconnect the sensor from the PCM and perform resistance and continuity tests on the relevant wires in the circuit. Compare all obtained readings with the values stated in the manual, and make repairs, or replace wiring as required to ensure that all electrical values fall within the manufacturer’s specifications. Reconnect all wiring after repairs are complete, clear the code, and rescan the system to see if the code returns.

Step 6

If the wiring checks out, and all electrical values (including the resistance of the sensor), fall within specifications, but the code persists, remove the affected EGT sensor from the vehicle for further testing. Note that while the sensor’s resistance might be within specified values, oil and carbon fouling can seriously affect the sensor’s operation.

Step 7

Inspect the sensor for evidence of carbon fouling, or the presence of other harmful deposits, and replace the sensor if such evidence is found, since there is no reliable to clean these sensors without running the risk of damaging them.

If however the sensor is not fouled, connect the multimeter to the correct pins so that the signal voltage can be measured when the sensor is heated. Be aware that the sensor might need to be grounded for this test the work- consult the manual on this important point.

Also, locate the temperature to resistance chart in the manual (or obtain one online), and use the heat gun to GENTLY heat the sensor, while monitoring the reading on the multimeter. The keyword here is GENTLY- do NOT heat the sensor to more than the maximum allowable temperature, details of which can be found in the manual.

Apply heat evenly in small increments, and use the laser-based thermometer regularly to obtain a temperature; collect at least five temperature readings, covering the sensor’s entire operating range. Compare these obtained readings with the manufacturer’s temperature-resistance chart and replace the sensor with an OEM part if one or more obtained readings do not conform to specifications.

Step 8

When replacing the EGT sensor, clear the code, and make sure all wiring is routed and secured away from hot exhaust components. Operate the vehicle for at least one complete drive cycle with a scanner attached to monitor the operation of the emissions control system in general, and the operation of the Exhaust Gas Temperature sensor in particular.

In the unlikely event that the code does return after one drive cycle, it is likely that there is an intermittent fault present, but be aware that faults of this type can be extremely challenging to find and repair. In some cases, it might be necessary to allow the fault to worsen before an accurate diagnosis and definitive repair can be made. However, refer to the SPECIAL NOTES at the start of the Troubleshooting section of this guide for some compelling reasons why resolving this code should not be delayed unduly.

Codes Related to P2035

P2036 – Relates to “Exhaust Gas Temperature Sensor Circuit High Bank 2 Sensor 2”

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