OBD-II trouble code
P2033: Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 2
An implausibly high number at the filter inlet is the one reading a module is not allowed to ignore, because it is what a runaway regeneration would look like — so the response is immediate, abrupt, and impossible for the driver to miss.
Quick facts
- System
- Powertrain
- Category
- Exhaust / Aftertreatment
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $120 – $750
- DIY difficulty
- Intermediate DIY
Browse every code in P2000–P20E8, or start from the full code library.
What does P2033 mean?
The behaviour of a vehicle with P2033 is what separates it from its low-side twin, and it comes down to what a high number at this position would mean if it were true.
A particulate filter is a ceramic honeycomb. Burning soot out of it releases heat, and the amount of heat released depends on how much soot is in there. Under the wrong conditions — a heavily loaded filter, a regeneration interrupted and restarted, a driver who switches off partway through — that burn can accelerate on itself and produce internal temperatures high enough to crack or melt the substrate. That is the failure mode every aftertreatment control strategy is written to avoid, and the filter inlet temperature is the number that would warn of it.
So when this circuit reports a value above anything the module considers physically possible, the strategy does not deliberate. It aborts any regeneration in progress, refuses to start another, and on most vehicles pulls power back as well. The driver notices at once: a warning lamp and a car that will not pull. Compare that with the low-side fault, where nothing changes and the code can sit unnoticed for months. Same sensor, same circuit, opposite presentation — because one direction is merely wrong and the other direction is alarming.
Electrically, a high reading almost always means the circuit is open rather than shorted to power. These sensors are read by holding the line up through an internal resistor and letting the sensing element pull it down; break the connection and there is nothing left to pull it down, so it rises to the top and stays there. There is very little under a vehicle carrying battery voltage anywhere near this lead, which is why a genuine short to power is the rare explanation and a broken connection is the common one.
Where those breaks come from is specific to this sensor's environment. Its tip lives in gas that swings between near-ambient and several hundred degrees during a regeneration, and it lives in that swing while sitting under the floor of a vehicle. Two things follow. First, the sensing element is repeatedly thermal-cycled, and cold water thrown up from a wet road onto a component at regeneration temperature is a genuine thermal shock — cracked tips and elements that fail open are ordinary outcomes, not exotic ones. Second, the lead and connector expand and contract through that same cycle, which is precisely how terminals fret, pins back out of housings, and a crimp that was sound for years opens up.
The practical consequence is that a fault like this is often intermittent before it is permanent. A vehicle that had one unexplained episode of reduced power that cleared on a restart, and now has a hard code, has usually been telling this story for a while. Asking about that history is worth more than any single meter reading, because it points at a marginal joint rather than a failed part, and a marginal joint is found by moving the harness rather than by testing it while it sits still.
Common causes
- Sensing element failed open after repeated thermal cycling between ambient and regeneration temperatures
- Sensor tip cracked by cold road spray striking a component at full regeneration heat
- Broken conductor inside the lead, typically at a crimp or where the harness leaves the sensor body
- Connector not fully latched, or a terminal backed out of its housing after thermal expansion cycling
- Fretted or oxidised terminals no longer making reliable contact
- Lead severed or pulled apart by a stone strike, a lift arm or debris on the underbody
- Harness broken at a bracket where it has been flexing against a fixed clip
- Sensor unscrewed or loose in its boss, breaking the ground path through the body on grounded designs
- Open shared reference or ground affecting this and other aftertreatment sensors together
- Short to a switched supply, uncommon here but possible where a repair has routed the lead badly
Symptoms
- Warning lamp and a noticeable loss of power appearing at the same moment
- Scan tool showing an exhaust temperature pinned at the very top of the scale, including on a cold engine
- Regeneration aborting partway through, sometimes with a burnt smell that stops abruptly
- Reduced power that clears on a restart and then returns, before becoming permanent
- Cooling fans running hard immediately after an aborted regeneration
- Filter loading and restriction codes accumulating because regenerations no longer complete
- Rough or laboured feel under load once the module has derated
- Fault appearing on rough roads, over speed bumps or shortly after underbody work
- Visible damage to the sensor lead or a connector hanging free under the vehicle
Diagnostic steps
- 1.Look at the reading on a stone-cold engine. A sensor reporting extreme heat on a vehicle that has stood overnight is describing an open circuit, and that observation alone rules out an actual exhaust condition.
- 2.Inspect the sensor, its lead and its connector physically before testing anything. Open circuits on this position are usually mechanical, and a lead pulled apart or a connector hanging loose is often visible in under a minute.
- 3.Ask what happened recently. Underbody work, a jack or lift arm placed against the exhaust, an impact, or a lost heat shield all break this lead, and the history frequently identifies the fault faster than a meter.
- 4.Check the connector is fully latched and no terminal has backed out. Thermal cycling works pins loose here, and a pin that looks seated can still have lost its contact spring.
- 5.Bridge the two sensor pins at the connector with a jumper. If the reading swings to the cold end of the scale, the harness to the module is sound and the fault is the sensor or its own lead.
- 6.If bridging changes nothing, test continuity of each conductor back to the module while flexing the harness through its run. An open that only appears under movement will pass a static test.
- 7.Measure the sensor's own resistance. A failed-open element reads as an infinite value that does not change as the tip is warmed.
- 8.Verify the sensor is tight in its boss and, on designs that ground through the body, that the mounting point is clean.
- 9.If other aftertreatment sensors are reading oddly at the same time, test the shared ground and reference before replacing any individual sensor.
- 10.After repair, route and clip the lead away from the pipe and moving components, then command a regeneration and confirm it runs to completion instead of aborting.
Repair cost
$120 – $750
Diagnosis is $90 to $180, and the jumper test that separates sensor from harness costs nothing beyond the time. The sensor is $60 to $260 with 0.5 to 1.5 hours of labour. Repairing a broken lead, replacing a damaged connector body or re-terminating a failed crimp is $80 to $300 and is often the whole job on this failure mode. A seized sensor that shears in its boss adds $150 to $400 for extraction or a repaired thread. The derate clears once the fault is fixed, so there is no separate cost for that — but a filter that has gone weeks without completing a regeneration may need cleaning at $900 or more.
Estimate your repair
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Open the Repair Cost Estimator with exhaust gas temperature sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.