Category Archives: AWD

Subframe Lockbolt install for Subaru WRX/STi

Subframe Lockbolt install for Subaru WRX/STi:

This is a step by step guide on installing a subframe lockbolt kit into the rear subframe of your 02-07 Subaru Impreza WRX/STi.

Subframe Lockbolt install for Subaru WRX/STi: Where these two red arrows point to are where the lockout bolts will be installed.

The rear subframe is isolated by rubber bushings which allow some movement relative the WRX/STi chassis. This movement can be the source of a rubbery feeling during launch and hard cornering. Enough rear subframe movement may alter the rear toe settings and affect handling during advanced driving. Depending on which lockbolt brand you use the adapter portion may not sit flush to the subframe surface, this is part of the design and is OK.

The lockbolt is not designed to stop vertical movement of the rear subframe. It is meant to limit movement in the horizontal plane. PB Blaster will soften the factory undercoating spray thus making a mess. WD-40 is not as aggressive so less black mess is made.

Antilock Brake System For Early Subaru Part 2:

Antilock Brake System for Early Subarus:

ABS Service And Brake Bleeding Procedures:

Antilock Brake System for Early Subarus: The first Subaru rally car the Legacy RS relied upon the bousch/nippon ABS units to perform on the WRC circuit.

Always check the fluid level of the master cylinder and bleed the wheel cylinders following the procedure listed in the service manual. When the HCU has been removed and/or replaced, the fluid must be drained. Replace the cone screws with bleed screws and attach a hose to drain fluid to a container.

Antilock: ABS Service And Brake Bleeding Procedures: A early Subaru Nippon ABS unit ECU.

Use extreme care when performing this procedure to prevent damage to the internal components of the HCU. Do not apply AV signal for more than 5 seconds for each application. If no AV signal is received, it is not necessary to close bleed screw between brake pedal applications.

Antilock Brake System Notes and Cautions:

The ECU on early Subaru ABS systems can only display one trouble code–the lowest numbered code. Correct the fault indicated by the trouble code and recheck ECU for another code. Repeat the self-diagnostic procedure listed above, and the next highest code will be displayed. Refer to the appropriate model year service manual for the trouble codes and corrective actions. While the ABS ECU is in the fault mode, the ABS will go to fail-safe and remain passive under all braking conditions. The brake system will function as a conventional power-assisted system without ABS.

Maintenance:Subaru Periodic Maintenance Part 3:

Maintenance: Subaru Periodic Vehicle Maintenance Services:

Brake Fluid:

Many late model Subaru vehicles are equipped with ABS braking systems. The added complexity of these systems provides an additional incentive for following the recommended brake fluid replacement interval of 30 months or 30,000 miles. Brake fluid accumulates water and other contaminants over time. These contaminants can attack the internal parts of the brake system, compromising its performance and possibly causing brake failure.

Maintenance: Subaru Periodic Vehicle Maintenance Services: Make sure to replace brake fluid at least every 30 months of 30,000 miles. At least once a year if the Subaru sees heavy track use.

The brake master cylinder has a semi-transparent reservoir, making it possible to check the fluid level without removing the reservoir cover. This minimizes the exposure to outside air and limits the amount of moisture that can reach the brake fluid. The fluid level will drop as the brake shoes and pads wear, but the reservoir is large enough to compensate for these changes. If the fluid level is very low, it’s a sure sign the brake pads or shoes are nearly worn out, or there is a leak in the brake system.

Note: When the brake fluid level in the reservoir tank is lower than the specified limit, the brake fluid warning light in the combination meter will come on.

Subaru warns against mixing brake fluids from different manufacturers. Doing so may degrade the quality of the fluid. Only DOT 3 or 4 brake fluid should be used in any Subaru vehicle preferably Subaru brake fluid if you are not going to do a track day build. Consult the service manual for vehicle specific brake bleeding procedures.

Subaru OEM Brake Fluid:

Subaru SOA868V9220 Brake Fluid – 1 Pint

Antilock Brake System for Early Subaru Part 1:

Antilock Brake System for Early Subarus:

A variety of antilock brake system (ABS) have been installed in Subaru vehicles since the first systems were installed in the 1990 Legacy.  In the sections that follow, we’ll give you a brief overview of each system and explain proper diagnostic techniques.

Antilock Brake System for Early Subarus: A Subaru SVX ABS system.

Antilock Brake System for Early Subarus:

Early Subaru Antilock Brake Systems:

The original Subaru Legacy Antilock Brake System (ABS) was licensed by Bosch and manufactured by Nippon ABS, Ltd. The system electronically controls brake fluid pressure supplied to the brake system. This control helps to prevent “wheel lockup” during braking on slippery surfaces and emergency situations. The system includes a fail-safe feature, which indicates a malfunction by illuminating the warning lamp. The system is then returned to a conventional power brake system. The four channel system provides accurate individual wheelspeed control and improves the directional stability of the vehicle during braking.

Antilock Brake System (ABS) Components

• Tone wheels (4)

• Speed sensors (4)

• Electronic control unit (ECU)

• Hydraulic control unit (HCU)

• G sensor (manual transmission models)

• Warning lamp

A tone wheel is attached to each wheel hub and rotates at the same speed as the hub. The magnetic speed sensor is mounted in the axle housing. The notched tone wheel acts as a reluctor which modulates the magnetic field of the speed sensor. The tone wheels are individually replaceable.

The speed sensor provides an alternating voltage signal to the ECU. The alternating voltage and frequency corresponds to wheelspeed.

Maintenance:Subaru Periodic Maintenance Part 2:

Maintenance: Subaru Periodic Vehicle Maintenance Services:

Maintenance: Subaru Periodic Vehicle Maintenance Services: Often the best value and best parts come from Subaru themselves and often aftermarket replacement parts will be of substandard quality.

Fuel Filter and Fuel Lines:

There’s no easy way to check the inside of a fuel filter for dirt or other contamination buildup. That’s why a 30 month or 30,000 mile replacement interval is prescribed. If the customer happens to buy a tank-load of bad gasoline before reaching this interval, it will be necessary to replace the fuel filter ahead of time. There’s no way to clean the filter—replacement is the only option. Remove the battery negative cable before you begin work on the fuel filter. Remember gasoline is a very flammable substance.

The fuel filter is just one small part of the fuel system. The fuel system includes many sections of steel and rubber fuel line that run the length of the vehicle several times. The fuel pump, fuel tank, and fuel pressure regulator are just a few of the other parts of the fuel system. While you’re replacing the fuel filter, don’t forget to check the condition of the rest of the fuel system.

Maintenance: Subaru Periodic Vehicle Maintenance Services: Pictured is a Subaru STi fuel system. Making sure your filter is in good condition and is replaced regularly will prevent problems from occurring.

If any of the rubber hoses (especially the ones that were opened up to replace the filter) look damaged or frayed, they must be replaced before they can cause any further damage. Weak fuel hose clamps should be replaced, and the new ones must be properly positioned and tightened to specification.


Subaru 42072PA010 Fuel Filter

Maintenance:Subaru Periodic Maintenance Part 1:

Maintenance: Subaru Periodic Vehicle Maintenance Services:

Vehicle maintenance is an important factor for proper vehicle operation. It’s the vehicle owner’s responsibility to ensure that fluid levels (engine oil, coolant, etc.) are checked frequently, in accordance with the instructions in the Subaru owner’s manual. However, many ‘gas and go’ vehicle owners may not take the time to fulfill these basic responsibilities. This places added importance on the performance of periodic maintenance services. If the Subaru owner isn’t looking after his vehicle, it falls to the automotive service professional to ensure that proper maintenance procedures are performed.

Maintenance: Subaru Periodic Vehicle Maintenance: It’s always important to periodically check your Subaru’s timing belt for wear and tear.

The frequency of scheduled inspection and maintenance services required by late model Subaru vehicles is minimal when compared with vehicles of the past. For example, even the very commonly used term ‘tune-up’ has lost most of its original meaning. In the old days, a ‘tune-up’ meant fresh spark plugs, points and condenser, and basic engine adjustments such as timing, idle mixture and idle speed. Modern technology has eliminated the need for many of these adjustments and replacement parts. However, the tune-up is alive and well— only its definition has changed.

While the number of vehicle items requiring regular replacement has decreased, the number of items needing periodic inspection has not. Whether you call it a tune-up or something else, this service offers an excellent opportunity for all engine belts, hoses and ignition wires to be checked for wear and tension. Old tune-up standbys like spark plugs, fuel and air filters are still on every Subaru vehicle and still require periodic inspection and replacement as necessary.

The same applies to all other items on the Subaru maintenance schedule. The important thing is to carefully inspect each item. If additional corrective action is required, now is the time to find out.

Subaru OBD-2 Diagnostic Trouble Codes:

Subaru OBD-2 Diagnostic Trouble Codes:

This is a list of the OBD-2 diagnostic trouble codes for Subaru Impreza, WRX, STi, Forester, and Legacy.

Subaru OBD2 Diagnostic port

P0031 Front oxygen (A/F) sensor heater circuit low input
P0032 Front oxygen (A/F) sensor heater circult high input
P0037 Rear oxygen sensor heater circuit malfunction
P0038 Rear oxygen sensor heater circuit high input
P0065 Air assist injector solenoid valve malfunction
P0066 Air assist injector solenoid valve circuit low input
P0067 Air assist injector solenoid valve circuit high input
P0100 Mass or Volume Air Flow Circuit Malfunction
P0101 Mass or Volume Air Flow Circuit Range/Performance Problem
P0102 Mass or Volume Air Flow Circuit Low Input
P0103 Mass or Volume Air Flow Circuit High Input
P0104 Mass or Volume Air Flow Circuit Intermittent
P0105 Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
P0106 Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
P0107 Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input
P0109 Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent
P0109 Intake Air Temperature Circuit Malfunction
P0111 Intake Air Temperature Circuit Range/Performance Problem
P0112 Intake Air Temperature Circuit Low Input
P0113 Intake Air Temperature Circuit High Input
P0114 Intake Air Temperature Circuit Intermittent
P0115 Engine Coolant Temperature Circuit Malfunction
P0116 Engine Coolant Temperature Circuit Range/Performance Problem
P0117 Engine Coolant Temperature Circuit Low Input
P0118 Engine Coolant Temperature Circuit High Input
P0119 Engine Coolant Temperature Circuit Intermittent
P0120 Throttle/Petal Position Sensor/Switch A Circuit Malfunction
P0121 Throttle/Petal Position Sensor/Switch A Circuit Range/Performance Problem
P0122 Throttle/Petal Position Sensor/Switch A Circuit Low Input
P0123 Throttle/Petal Position Sensor/Switch A Circuit High Input
P0124 Throttle/Petal Position Sensor/Switch A Circuit Intermittent
P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control
P0126 Insufficient Coolant Temperature for Stable Operation
P0128 Thermostat malfunction
P0130 O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)
P0131 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
P0132 O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)

P0133 O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)

P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
P0137 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
P0138 O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
P0140 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
P0141 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
P0142 O2 Sensor Circuit Malfunction (Bank 1 Sensor 3)
P0143 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
P0144 O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)
P0145 O2 Sensor Circuit Slow Response (Bank 1 Sensor 3)
P0146 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 3)
P0147 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)
P0150 O2 Sensor Circuit Malfunction (Bank 2 Sensor 1)
P0151 O2 Sensor Circuit Low Voltage (Bank 2 Sensor 1)
P0152 O2 Sensor Circuit High Voltage (Bank 2 Sensor 1)
P0153 O2 Sensor Circuit Slow Response (Bank 2 Sensor 1)
P0154 O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)
P0155 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
P0156 O2 Sensor Circuit Malfunction (Bank 2 Sensor 2)
P0157 O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
P0158 O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
P0159 O2 Sensor Circuit Slow Response (Bank 2 Sensor 2)
P0160 O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)
P0161 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
P0162 O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)
P0163 O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)
P0164 O2 Sensor Circuit High Voltage (Bank 2 Sensor 3)

P0165 O2 Sensor Circuit Slow Response (Bank 2 Sensor 3)
P0166 O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)
P0167 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3)
P0170 Fuel Trim Malfunction (Bank 1)
P0171 System too Lean (Bank 1)
P0172 System too Rich (Bank 1)
P0173 Fuel Trim Malfunction (Bank 2)
P0174 System too Lean (Bank 2)
P0175 System too Rich (Bank 2)
P0176 Fuel Composition Sensor Circuit Malfunction
P0177 Fuel Composition Sensor Circuit Range/Performance
P0178 Fuel Composition Sensor Circuit Low Input
P0179 Fuel Composition Sensor Circuit High Input
P0180 Fuel Temperature Sensor A Circuit Malfunction
P0181 Fuel Temperature Sensor A Circuit Range/Performance

P0182 Fuel Temperature Sensor A Circuit Low Input
P0183 Fuel Temperature Sensor A Circuit High Input
P0184 Fuel Temperature Sensor A Circuit Intermittent
P0185 Fuel Temperature Sensor B Circuit Malfunction
P0186 Fuel Temperature Sensor B Circuit Range/Performance
P0187 Fuel Temperature Sensor B Circuit Low Input
P0188 Fuel Temperature Sensor B Circuit High Input
P0189 Fuel Temperature Sensor B Circuit Intermittent
P0190 Fuel Rail Pressure Sensor Circuit Malfunction
P0191 Fuel Rail Pressure Sensor Circuit Range/Performance
P0192 Fuel Rail Pressure Sensor Circuit Low Input
P0193 Fuel Rail Pressure Sensor Circuit High Input
P0194 Fuel Rail Pressure Sensor Circuit Intermittent
P0195 Engine Oil Temperature Sensor Malfunction
P0196 Engine Oil Temperature Sensor Range/Performance
P0197 Engine Oil Temperature Sensor Low
P0198 Engine Oil Temperature Sensor High
P0199 Engine Oil Temperature Sensor Intermittent

ATF Power Steering Fluid Replacement Subaru STi/WRX:

ATF Power Steering Fluid Replacement Subaru STi/WRX:

This is a step by step guide in replacing the ATF power steering fluid on your Subaru STi/WRX. This is pretty much a two person job unless you have a suction gun. I like to use Mobil 1 ATF Synthetic fluid.

ATF Power Steering Fluid Replacement Subaru STi/WRX: A how to guide on replacing the power steering fluid on a Subaru WRX/STi.


Mobil 1 Synthetic Automatic Transmission Formula

1.) Open hood and remove two 12 mm bolts on intake scoop. Remove the scoop (lift up right side and it will pop off).

2.) Remove cap from power steering reservoir.

3.) Raise the car up (use jack stands “Safety first”), not to high. A person must sit in the car while another person fills the power steering reservoir.

4.) Under the car – Remove the Plastic engine cover under the car, using the 12 mm socket (5 bolts) and flat tip screw driver (4 clips).

5.) Remove the center jack plate, using 14 mm socket (4 nuts), and 12mm socket and 12 mm wrench (2 rear bolts & 2 front nuts/bolts).

ATF Power Steering Fluid Replacement Subaru STi/WRX:

6.) Place a oil pan under the power steering gear box (just above jack plate location).

7.) Using the pliers slide one of the clips off the rubber hose (pipe joint) on the power steering gear box. Fluid will drain out immediately, so have that pan already in place under the hose.

ATF power steering fluid: The rubber hoses in the middle are the ones to drain from.

8.) Slowly pour in some ATF into the reservoir, while another person sits in the car and SLOWLY turns the steering wheels from lock to lock – perform this at least 3 times. Watch the fluid in the reservoir so that it doesn’t drain out, and watch under the car to see when the old fluid is flushed out. The OEM fluid was brown and I used Mobile 1 ATF Synthetic which was red, so I could see when all the old fluid was flushed.

9.) Re-attach rubber hose (pipe joint) and slide the clip back into place. Put jack plate back on and put plastic undercover back on.

10.) Pour in ATF to the MAX cold line on the reservoir and be ready to add more when the person turns the steering wheel.

ATF Power Steering Fluid Replacement Subaru STi/WRX:

11.) Slowly turn the steering wheel lock to lock (3x or more) and watch the reservoir until bubbles stop appearing. Add ATF as needed! DO NOT LET THE RESERVOIR GET TOO LOW!!! This will suck more air into the system.

12.) Start the car and Slowly turn the steering wheel lock to lock (3x or more) and watch the reservoir until bubbles stop appearing. Add ATF as needed.

13.) Lower car onto the ground. Slowly turn the steering wheel lock to lock (3x or more) and watch the reservoir until bubbles stop appearing. Add ATF as needed.

14.) “In case the following happens, leave it about a half an hour and then do” STEP 11 to STEP 13 again:
a. Fluid level changes over 3 mm (0.12 in)
b. Bubbles remain on the upper surface of the fluid
c. Grinding noise is generated from power steering pump.

15.) Replace power steering cap and reinstall the intake scoop.

Now enjoy your smoother steering with your brand new ATF on your Subaru WRX/STi!

Tools needed:
Flat tip screw driver
10 mm socket
12 mm socket
14 mm socket
12 mm wrench
Pliers
Drain pan