P2002 Diesel Particulate Filter Efficiency Below Threshold (Bank 1)
P2002 is a generic OBD2 powertrain code. It means “Diesel Particulate Filter Efficiency Below Threshold (Bank 1)” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Ask the AI about P2002 on your car- System
- Powertrain (P)
- Code type
- Generic (SAE)
- Range
- P20xx
- Urgency
- Moderate
What P2002 means
The diesel particulate filter (DPF) traps soot from the exhaust. Judging by the pressure difference across it, the computer concluded the filter is no longer filtering well — often because it is cracked, or because the pressure sensor is misreading.
Symptoms
- Usually nothing but the lamp
- Black smoke or soot at the tailpipe
- A failed emissions test
Most likely causes
- A faulty differential-pressure sensor, or a split or blocked sensor hose
- A cracked or damaged filter
- A removed or tampered-with filter
- An exhaust leak ahead of the filter
What to check first
- Inspect the pressure-sensor hoses for splits and blockages
- With the engine off, the sensor should read close to zero
- Inspect the filter and the exhaust for leaks
Can I keep driving with P2002?
Drivable — plan the repair soon
Yes, for now. The engine isn’t at risk, but the car will likely fail its emissions inspection and should be repaired soon.
What the wording tells you
“Efficiency below threshold” means a monitor measured how well a component does its job — a catalyst, a trap, a filter — and found it below the limit the standard allows. A sensor that misreads produces the same result, so the sensors are worth checking before the component is replaced.
Bank 1: engines with two rows of cylinders — V6, V8, boxer — have two banks. Bank 1 is the side that holds cylinder 1, bank 2 the other side; an inline engine has only bank 1.
How P2002 breaks down
Powertrain. Engine, transmission, fuel and emissions — the codes behind the check engine lamp.
Generic code: defined by SAE, the same on every make.
Fuel & air metering and emission controls.
The specific fault within this range.
Where to look: Fuel & air metering and emission controls
Codes in these ranges cover the parts that decide how much air and fuel reach the engine and how the exhaust is treated on the way out: variable valve timing, oxygen-sensor heaters, turbo boost control, the electronic throttle and accelerator pedal, intake runners, NOx sensors and — on diesels — the particulate filter and the AdBlue (SCR) system.
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Frequently asked
What does P2002 mean?
P2002 is a generic OBD2 powertrain code. It means “Diesel Particulate Filter Efficiency Below Threshold (Bank 1)” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker. The diesel particulate filter (DPF) traps soot from the exhaust. Judging by the pressure difference across it, the computer concluded the filter is no longer filtering well — often because it is cracked, or because the pressure sensor is misreading.
Can I drive with P2002?
Yes, for now. The engine isn’t at risk, but the car will likely fail its emissions inspection and should be repaired soon.
What causes P2002?
A faulty differential-pressure sensor, or a split or blocked sensor hose; A cracked or damaged filter; A removed or tampered-with filter; An exhaust leak ahead of the filter.
How do I clear P2002?
Fix the cause first, then clear it with any OBD2 scanner or app. Once the fault is gone the car also clears it on its own: the check engine lamp goes off after the self-test passes on three drive cycles in a row, and the stored code ages out after about 40 warm-ups. Clearing without a repair only hides it for a while — and resets the readiness monitors an emissions inspection looks at.
Is P2002 the same on every car?
Yes. P2002 is a generic SAE J2012 code, so its definition is identical on every make and model. What differs is the cause behind it and the repair procedure, which depend on the engine — that’s why the assistant on this page asks for your car.
Guides
Definitions: the generic SAE J2012 codes from Brimly’s offline dictionary (data version 2026.09). Causes and advice are general guidance for all makes — the service information for your car has the last word.