P189C on Toyota
Diesel Particulate Filter Restriction - Forced Limited Power
P189C on Toyota vehicles indicates diesel particulate filter restriction - forced limited power. Au7o has documented this code across 1 Toyota model — most commonly on Supra. This code is set on diesel vehicles when the diesel particulate filter (DPF) is so restricted that the engine computer forces the vehicle into a reduced-power (limp) mode to protect the engine and exhaust system. The DPF traps soot from the exhaust and normally burns it off during regeneration, but if it becomes overloaded with soot or ash, exhaust backpressure rises dangerously high. The computer detects this excessive restriction via pressure sensors and deliberately limits power to prevent damage and force the driver to address it. This is considered a serious code, often requiring a forced regeneration or, in severe cases, DPF cleaning or replacement.
Common Causes of P189C
- •Clogged DPF from excessive soot accumulation
- •Incomplete or failed DPF regeneration (frequent short trips)
- •Ash buildup in an aged DPF requiring cleaning/replacement
- •Faulty DPF differential pressure sensor or hoses
- •Faulty EGR system increasing soot production
- •Failed or contaminated fuel injectors causing excess soot
- •Exhaust temperature sensor faults preventing regeneration
- •Low fuel or interrupted/aborted regeneration cycles
P189C on Toyota by Model
Toyota Supra(1 issue)
- ZF 8HP Transmission Rough Low-Speed Shifts2020-2025
The ZF 8HP51 automatic transmission exhibits rough or jerky shifts at low speeds, particularly 1st-to-2nd and 2nd-to-3rd gear changes during city driving. The mechatronic unit's valve body can develop wear causing harsh engagement. Cold weather worsens symptoms.
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View P189C across all makes →Frequently Asked Questions
What does P189C mean on Toyota?▼
P189C stands for "Diesel Particulate Filter Restriction - Forced Limited Power." This code is set on diesel vehicles when the diesel particulate filter (DPF) is so restricted that the engine computer forces the vehicle into a reduced-power (limp) mode to protect the engine and exhaust system. The DPF traps soot from the exhaust and normally burns it off during regeneration, but if it becomes overloaded with soot or ash, exhaust backpressure rises dangerously high. The computer detects this excessive restriction via pressure sensors and deliberately limits power to prevent damage and force the driver to address it. This is considered a serious code, often requiring a forced regeneration or, in severe cases, DPF cleaning or replacement. On Toyota specifically, this code is documented across 1 model.
What causes P189C on Toyota vehicles?▼
Common causes on Toyota: Clogged DPF from excessive soot accumulation, Incomplete or failed DPF regeneration (frequent short trips), Ash buildup in an aged DPF requiring cleaning/replacement, Faulty DPF differential pressure sensor or hoses, Faulty EGR system increasing soot production. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P189C on a Toyota?▼
Repair costs vary widely depending on the root cause and specific Toyota model.
Which Toyota models have P189C documented?▼
Au7o has documented P189C on 1 Toyota model: Supra.