P0551
Power Steering Pressure Sensor Circuit Range/Performance
The appearance of the standard OBD2 trouble fault code P0551 is an indicator that your vehicle ECU triggered a threshold alert for "Power Steering Pressure Sensor Circuit Range/Performance". Understanding the root component breakdown helps avoid expensive diagnostic fees.
Driver's Summary
A P0551 fault code points directly to a problem with power steering pressure sensor circuit range/performance that the ECM has confirmed over multiple drive cycles. You may notice idle surges during tight turns, check engine light, all of which are direct consequences of this malfunction. This code won't leave you stranded, but it indicates a real issue that will only get easier and cheaper to fix sooner rather than later.
Symptoms
Idle surges during tight turns, check engine light
Common Causes
- Clogged PSP sensor port
- Contaminated power steering fluid
- Faulty sensor
- Intermittent wiring issue
How to Fix
- 1 Clean PSP sensor and port
- 2 Flush power steering fluid
- 3 Replace PSP sensor
- 4 Check connector contacts
Technical Explanation
To set P0551, the PCM samples the affected circuit multiple times per second, comparing live readings against manufacturer-programmed operating windows. A two-trip detection strategy is employed for most powertrain codes: the fault must be detected on one drive cycle, the vehicle key-cycled off, and the fault detected again on the next drive cycle before the MIL illuminates and a permanent DTC is stored. After two failed drive cycles, the code transitions from a pending to a confirmed DTC, and the PCM activates the MIL. Clearing the code without repairing the fault will result in re-illumination within one to two complete drive cycles.
Is It Safe to Drive?
Immediate safety risk is low with P0551 active. The primary concern is regulatory — this fault will cause a failed emissions test — and the secondary risk is that the small root cause (clogged psp sensor port) becomes a larger problem if ignored for months.
Mechanic's Pro Tip
Before replacing any component on P0551, spend 5 minutes inspecting the wiring harness and connector first — corrosion, chafed insulation, and backed-out pins cause the majority of these faults and cost nothing to fix. Use a multimeter to measure voltage drop across the connector pins under load; anything above 0.1V indicates excessive resistance that will cause intermittent failures even after replacing the sensor.
Fluid flush: $80 - $120; Sensor replacement: $100 - $200