P2031 to P2036: exhaust gas temperature sensor bank 1 sensor 2

A diesel with the full after-treatment stack has an oxidation catalyst, a particulate filter and often an SCR system. Each stage has a temperature window it works within, and the ECU needs to know the temperature at each point.

That means multiple exhaust gas temperature sensors, numbered by position.

Code	Meaning
P2031	EGT sensor circuit, bank 1 sensor 2
P2032	Circuit low, same sensor
P2033	Circuit high, same sensor
P2034	EGT sensor circuit, next position
P2035	Circuit low, next sensor
P2036	Circuit high, next sensor

The codes run in threes per sensor: general circuit, circuit low, circuit high.

Sensor 1 codes: P0545 and P0546 exhaust gas temperature sensor.

Position determines consequence

Sensor numbering follows the direction of exhaust flow.

• Sensor 1 — before or at the oxidation catalyst. Protects the turbocharger and controls the start of regeneration.
• Sensor 2 — usually before the particulate filter. This is the one that decides whether regeneration reached the temperature it needed.
• Sensor 3 and beyond — after the filter, or around the SCR catalyst, where the reductant dosing strategy needs temperature.

A sensor 2 fault typically blocks regeneration entirely, because the ECU cannot confirm the filter reached the required temperature and will not risk running the process blind.

Why blocked regeneration matters

Soot accumulates whether or not the filter can regenerate. A DPF that cannot burn off soot fills steadily until:

• The warning lamp comes on.
• Power is reduced to limit further soot production.
• Eventually the filter blocks and needs forced regeneration or removal for cleaning.

DPF light on, what to do, P2002 and P2463 DPF efficiency and soot and DPF forced regeneration scanner procedure.

So a sensor left unfixed becomes a filter replacement, and the filter is the far more expensive of the two. That is the practical argument for treating this as urgent.

The oil dilution consequence

Regeneration works by injecting extra fuel late in the combustion cycle to raise exhaust temperature. Some of that fuel washes past the rings into the sump.

A vehicle that keeps attempting regeneration and failing does this repeatedly. The dipstick level rises, and diluted oil does not protect bearings.

Check the oil level on any diesel with a regeneration fault. Above maximum means change it, not top it up: oil light flickering at idle.

Diagnosis: the cold comparison

The decisive test, as for every temperature sensor.

After the vehicle has stood overnight, all EGT sensors must read approximately ambient and approximately the same as each other. Any that disagrees is the faulty one.

Reading after cold soak	Verdict
All within a few degrees	Sensors plausible
One far off	That sensor is faulty
Pinned at −40 or 900+	Circuit fault, not a measurement
Plausible but never rises when driving	Stuck sensor

Then log a drive and confirm each sensor rises under load, in the order the exhaust flows.

Causes

Heat cycling, thousands of times from ambient to 700 °C. These are consumables.

Wiring fatigue where the cable leaves the sensor body and where it is clipped along the exhaust.

Connector corrosion, in the underbody airflow.

Physical damage during exhaust work — the harness is easy to snag.

A seized thread, which is not a fault until removal is attempted. Sensors in place for a decade frequently shear. Factor that into the job before starting.

What a healthy regeneration looks like

Useful for interpreting the data:

1. Soot load reaches the trigger threshold.
2. Post-injection begins.
3. Sensor 2 temperature climbs toward 600 °C.
4. It holds for ten to twenty minutes.
5. Soot load falls sharply.
6. The cycle ends and temperatures return to normal.

If temperature never climbs, regeneration is not happening. If it climbs and soot does not fall, the filter may be blocked with ash rather than soot: P242F DPF ash accumulation.

Sequence

1. Compare all EGT sensors from cold.
2. Check the connector and harness along the exhaust.
3. Log a drive and confirm each sensor responds.
4. Check soot load and time since the last successful regeneration.
5. Check the oil level for dilution.
6. Replace the faulty sensor, allowing for a seized thread.
7. Confirm a regeneration completes afterwards before considering the job done.

Try it on the free tier of the app — pair an ELM327 adapter and log every exhaust temperature sensor plus soot load. Watching one full regeneration succeed is the proof the repair worked.