Common Problems and Error Codes
Source: RX8Club.com - New and Potential Owners START HERE! Author: RIWWP
General Issues to Keep in Mind
Troubleshooting subforum: 2004-2008 | 2009+
DIYs subforum: 2004-2008 | 2009+
Most problems that crop up in the 8 start very small and get serious because they aren't addressed. For example coils start going bad, plugs then start getting fouled from excess unburnt fuel, unburnt fuel rapidly degrades cat life, clogged cat can over stress the seals and over cook the O2 sensors, localize heat too much which accelerates oil breakdown and increases engine wear...
Most of the owners that remain trouble free are trouble free because they keep on top of their oil changes, their oil level, and their ignition health.
Then again, that stuff is like taking cholesterol medication and regular exercise for your heart. They help prevent problems, but it doesn't eliminate risk and it doesn't mean that you still won't die of a heart attack. Mazda factory QC over the engine tolerances has improved quite a bit, but it is entirely possible to be sitting on an engine waiting for any chance it can to fail. It's also entirely possible to completely ignore all the recommendations and get 160,000+ miles out of the engine (one owner came on here thinking her engine was blown, come to find out it was just badly flooded, but she didn't know anything about rotaries and still had it healthy at 160,000 without doing what she should have)
It very is much like a heart, or lungs, or whatnot. All you can do is reduce the risk of failure.
Cooling and Lubrication are 99% of the battle to keep these engines healthy. Mazda didn't have enough of either from the factory, a flaw that puts us behind the curve. Several mods that are common can go a long way towards improving engine live. Namely the ReMedy water pump and thermostat, BHR ignition upgrade, COBB AccessPORT (for the part that allows you to monitor temps and set a lower threshhold for the radiator fans). Even removing the cat and going with a midpipe helps I think, as it helps keep heat away from the engine, and you don't have to worry about a clogged cat causing more problems. My engine was perfect until my cat failed, and it's never been right since. In spec, not replaceable point, but not back to the above average that it was. If you have a 2009 or newer, you have a Series2, along with the improvements to the engine that should mostly solve the lubrication problems. They still need better cooling.
But you also have the warranty. 100,000 miles, 8 years for the engine core. (Mazda SSP77) (if you are in that and outside powertrain, a "free engine" may still cost you ~$500 for all the fluids, gaskets, etc... associated with the engine, but not part of it)
Another source of problems is repetitive short trips, without getting the engine to temperature for at least a few minutes. Limited internal temp, and a proportionally larger amount of running time is under temp, increases carbon buildup dramatically, which leads to all sorts of further problems.
Specific Issues
TSBs (Technical Service Bulletins)
You should familiarize yourself with the official Mazda TSBs here: TSBs - Technical Service Bulletins
TSBs ARE NOT RECALLS! (RX8Club TSBs) They are Technical Service Bulletins, and are nothing more than a set of instructions from the factory to the dealers to tell them how to handle specific customer complaints. You will only have warranty coverage on a TSB IF YOU HAVE AN ACTIVE WARRANTY THAT COVERS THAT AREA OF THE CAR.
Misfires
Misfires are shown by a blinking check engine light (CEL), and are usually caused by a failing coil, failing plug wire, and/or failing spark plug. They can also be caused by cat failure, engine failure, vacuum leaks, fouled e-shaft sensor, dirty MAF, missing intake screens, aftermarket intake, failing intake valve actuators and a few other items. Start here for diagnosis: Suffering Misfire? Start Here (RX8Club)
Water in Tail Lights
Primarily a 2004 and 2005 problem, but can be seen across all years, including Series2, is a failing tail light gasket that lets moisture into the tail light lens. The improved gasket from the dealer helps, but isn't perfect. (RX8Club) You have options for repair, including DIY stuff and aftermarket gaskets. Drilling the tail light is a quick and easy solution, but is not recommended.
Clutch Pedal Assembly
The clutch pedal assembly is weak, and over time the pivot points wear through the mounting points, and eventually this will cause a failure in the assembly. A squeaking clutch when you push it and release it signals the issue getting worse. Getting a new assembly only solves it till that one breaks. There are a few options for fixing it, including welding at your local shop, buying a bracket from Race Roots, or buying a fully welded up assembly from BHR. As a result of the NHTSA investigation, Mazda has extended the warranty on the clutch pedal assemblies to 100,000 miles. (NHTSA PE09045) Only North American RX-8's.
Discoloration / Foam on the Oil Dipstick
Discolored or foamy substance on dipstick. The oil collects moisture in colder ambient temperatures. You may notice that the dipstick will look like it has weird discoloration. This has been described as foamy, milkshake, white crap, brown oil, etc... This is normal, and nothing of concern. (TSB 01-050/06) If you want, you can pay a large chunk of money to make it go away, but there is no harm to it, so just ignore it. Drive your engine harder to cook it off if it bothers you.
Official TSB: Milky Substance on Oil Dipstick (TSB 01-050/06)
Source: TSB 01-050/06 (PDF)
Mazda has issued a formal TSB for 2004–2005 RX-8s confirming this is a normal characteristic of the rotary engine:
- Root cause: In cold weather, moisture in blow-by gases condenses on the intermediate housing wall. This moisture reacts with engine oil to form the milky emulsion. It dissipates once the engine reaches full operating temperature.
- Mazda's position: The amount of moisture is within acceptable standards for common motor oils. Engine performance is NOT affected.
- Diagnostic check: Verify the coolant reservoir is full and there are no signs of coolant leakage (to rule out coolant seal / O-ring issues).
- Countermeasure: Mazda offers a ventilation kit (part
N3Y1-13-S80A) that replaces the oil filler pipe with a modified version and reroutes PCV hoses to reduce condensation. The kit includes new intake manifold gaskets (6), throttle body gasket (1), solenoid valves, and hoses. Labor: 1.2 hours. This fix was likely incorporated into Series 2 (2009+) production.
UK-spec RX-8s were sold exclusively in "full sport" configuration, which includes dual oil coolers instead of one. These paired coolers can over-cool the oil in cold weather, worsening condensation. Rotary Revs recommends scheduling one of the two annual oil changes for mid-winter to help keep the oil contaminant-free. (Source)
MAIC — "Marbles in a Can"
MAIC, or "Marbles in a Can" is a fortunately not common issue where you may hear a rattling sound from what sounds like the glovebox area, sometimes accompanied by inconsistent power loss. This is usually Secondary Shutter Valve (SSV) failure, which is typically caused by the valve getting over carboned, from oil burping or excessive oil vapors in the intake. Dealers will charge $2,000 or so to replace/clean, but you can DIY it for pretty much free.
Another possible cause for MAIC: Please help - Potential new owner question - MAIC
Power Steering
Mazda's QC missed a little issue with the coolant overflow tube, as it dumps overflow right onto our power steering connectors (the main power and torque sensor connections). Even without an "overheat" condition, overflow is possible, which in turn can affect the condition of these connections, causing various power steering issues, including complete failure. Then there are other issues that can crop up, including too much salt, dust, or debris interfering with the grease on the u-joint in the steering shaft, rack failure, and control module failure. The u-joint re-greasing is dirt cheap, easy to DIY, the connector quality isn't much harder (clean, replace harness for $100, or eliminate the connections and just make it solid wire). The rack and control module are REALLY expensive however. Most power steering issues were addressed by dealers replacing the module or the rack, when all the car needed was some clean connectors. Ideally, swap the coolant overflow hose to a longer one and run it farther down, where it won't bother anything. (RX8Club)
Main thread for Power Steering issues: Power Steering Failure
Motor Mounts
Our motor mounts collapse/degrade over time. This causes the car to shake more, especially at idle. This isn't the actual engine attachment points, but rather just the vibration dampeners. However it is not inherently a problem that you need to rush out and fix. Adding more vibration to the car isn't inherently bad, but can lead to other problems with rattles and joints wearing down. Most people choose to live with it.
Catalytic Converter Failure
This is too common unfortunately, as the heat and emissions level of the RX-8s engine is not friendly to cats at all. Additionally, most of the encountered failure points on an RX-8 cause misfires, and misfires will destroy a cat quickly. A clogged cat is dangerous to the engine, the car, and your life.
If it does fail, you have options: Catalytic Converters... Cats, Cats, Cats
Trouble Starting
There are numerous things that cause you to have difficulty starting. Here is a thread that goes into all the common ones: Starting Issues? Start Here
Quick diagnostic guide:
| Condition | Likely Causes |
|---|---|
| Won't start when hot (at operating temperature) | Slow starter motor, low engine compression, failing ignition coils |
| Won't start when cold (stood 3+ hours) | Engine flooding, faulty or low battery |
(Source)
Hot-Starting Problems
Hot-starting difficulty is a progressive issue that worsens over time. Early signs include a slightly longer crank time when the engine is warm. Eventually, the engine may refuse to restart until it has cooled down (15-20 minutes). This is not a normal characteristic — a healthy rotary should start just like any conventional engine.
Hot-starting problems should not be confused with engine flooding, which occurs when the engine is cold and cannot be resolved by simply waiting.
The only way to accurately diagnose the cause is a rotary-specific compression test. A conventional piston engine compression tester produces inaccurate results because it cannot measure each rotor face independently at a reliable cranking speed. (Source)
Rattling Noise at High RPM
A rattling, banging, or rasping noise at high RPM coupled with power loss can have two primary causes:
- Detonation (pinging/knocking): Unintentional fuel ignition caused by running too low an octane fuel. Try switching to a higher-octane fuel (e.g., Shell vPower Nitro+) to see if symptoms improve.
- Stationary gear bearing failure: Excess play in the e-shaft from worn bearings causes a clattering sound. This will eventually lead to complete engine failure.
(Source)
Coolant Level Warning Light Stays On
If the coolant level warning light stays on or flashes despite the coolant level being correct, the most likely cause is a faulty float in the coolant expansion tank. The float deteriorates over time, absorbs coolant, and sinks — triggering the false warning.
Source: Blue Print Technical Tip INF149 (PDF)
- The sensor float and sensor are not available separately — the entire expansion tank assembly must be replaced
- Replacement part: ADM59880 (Blue Print INF149) — Blue Print OEM-quality expansion tank with revised float
- Be careful when removing the lower coolant hose to avoid damaging the radiator outlet
The float can also be triggered by overfilling the expansion tank past the "Full" line, which submerges the float and causes it to take on water and sink. The warning may appear intermittently during hard acceleration or high revs as the degraded float starts to fail. A simpler alternative to replacing the tank is to unplug the sensor from the engine management system — this works with no ill effects. (Source)
Oil Cooler Line Corrosion
The RX-8 has three oil cooler lines. The line most prone to corrosion is located just in front of the passenger-side front wheel. Rust builds up on the line until it eventually bursts and leaks oil. Since the oil system operates under pressure, a leak causes oil pressure to drop, leading to excessive wear on the main engine bearings — requiring a full engine rebuild.
If you spot an oil leak in this area, do not start or drive the vehicle. Have the car recovered immediately.
Most cooler lines look worse for wear visually but are still functional — assessment relies heavily on a mechanic's experience. Aftermarket braided stainless steel cooler lines are available as a permanent fix. (Source)
Stationary Gear Bearing Failure
Stationary gear bearing failure is one of the most serious and relatively common faults in the RX-8. It develops over time rather than occurring suddenly, and is primarily caused by the ultra-low oil pressure at idle — the oil pump does not maintain enough pressure at very low RPMs to keep the e-shaft fully suspended in its oil film, allowing metal-to-metal contact with the bearing surfaces.
Symptoms to listen for:
- A low droning engine note at idle and throughout the rev range, accompanied by reluctance to rev at high RPM
- A sharp, loud clatter when initially starting the engine after being parked (described as sounding like someone banging on a metal dustbin with a baseball bat), lasting a couple of seconds
- A loud audible clatter at high RPM, which can be intermittent and related to engine temperature (similar to static/white noise)
Any combination of these sounds warrants immediate professional diagnosis. The only effective fix is a full engine strip-down and rebuild, or replacement of the bearings (which in most cases is best combined with a full rebuild anyway). (Source)
Low Compression — Apex Seal Wear
Apex seal wear is the primary cause of low engine compression. Due to the way apex seals are lubricated, the center of the flat seal surface wears faster than the outer edges. Over time, this creates a bowed profile that no longer seals correctly against the rotor housing, allowing gas leakage past the seals. The raised edges at the seal tips then concentrate pressure on a smaller surface area of the housing, causing chipping and scoring — often making the housings unusable for a rebuild.
Failing ignition coils accelerate this wear through "bore wash": unburnt fuel from incomplete combustion washes away the oil film that lubricates the seals, causing chattering and excessive wear.
The typical symptom progression is: difficulty restarting at operating temperature → low power output with uneven idle → cutting out at idle → refusing to start at all. The only effective fix is a full engine rebuild or engine replacement. (Source)
What Does the CEL Mean?
The Check Engine Light, also known as a CEL or MIL, is a light that is lit up on the dash by the ECU when it detects something wrong. It is NOT comprehensive about everything that could go wrong. In fact, your car could be on fire and it wouldn't know. The ECU only monitors EMISSIONS related items, due to the US laws that were enacted in the 1990s regarding emissions and OBD2 compliance.
How to Clear the CEL
- Disconnect the battery without reading the code to see what is wrong. This also clears your fuel trims, audio head unit presets, DSC/TCS learned parameters, and your car may idle roughly for the next few drive cycles.
- Go to an auto-parts store that will read the code for you for free, and then will clear it for you if you wish.
- Buy a code reader for less than a diagnostics fee at a shop, read and clear it yourself, and read all future codes on all your cars for free.
- Buy a bluetooth OBD2 dongle and pair it with your smartphone or tablet and an OBD2 app.
- Go to a shop and pay their one time diagnostic's charge to get the code for you.
- Go to a dealer and pay their even higher one time diagnostics charge to get the code, and then charge you even more for fixing it.
Common RX-8 DTC Codes
| DTC | Description | CEL |
|---|---|---|
| P0030 | Front HO2S heater control circuit problem | ON |
| P0031 | Front HO2S heater control circuit low | ON |
| P0032 | Front HO2S heater control circuit high | ON |
| P0037 | Rear HO2S heater control circuit low | ON |
| P0038 | Rear HO2S heater control circuit high | ON |
| P0076 | VDI solenoid valve control circuit low | OFF |
| P0077 | VDI solenoid valve control circuit high | OFF |
| P0101 | MAF sensor circuit range/performance problem | ON |
| P0102 | MAF sensor circuit low input | ON |
| P0103 | MAF sensor circuit high input | ON |
| P0107 | BARO sensor circuit low input | ON |
| P0108 | BARO sensor circuit high input | ON |
| P0111 | IAT sensor circuit range/performance problem | ON |
| P0112 | IAT sensor circuit low input | ON |
| P0113 | IAT sensor circuit high input | ON |
| P0117 | ECT sensor circuit low input | ON |
| P0118 | ECT sensor circuit high input | ON |
| P0122 | TP sensor No.1 circuit low input | ON |
| P0123 | TP sensor No.1 circuit high input | ON |
| P0125 | Insufficient coolant temperature for closed loop fuel control | ON |
| P0126 | Insufficient coolant temperature for stable operation | ON |
| P0130 | Front HO2S circuit problem | ON |
| P0131 | Front HO2S circuit low voltage | ON |
| P0132 | Front HO2S circuit high voltage | ON |
| P0133 | Front HO2S circuit slow response | ON |
| P0138 | Rear HO2S circuit high voltage | ON |
| P0139 | Rear HO2S circuit slow response | ON |
| P0171 | System too lean | ON |
| P0172 | System too rich | ON |
| P0222 | TP sensor No.2 circuit low input | ON |
| P0223 | TP sensor No.2 circuit high input | ON |
| P0300 | Random misfire detected | Flash/ON |
| P0301 | Front rotor misfire detected | Flash/ON |
| P0302 | Rear rotor misfire detected | Flash/ON |
| P0327 | KS circuit low input | ON |
| P0328 | KS circuit high input | ON |
| P0335 | Eccentric shaft position sensor circuit problem | ON |
| P0336 | Eccentric shaft position sensor circuit range/performance | ON |
| P0410 | AIR system problem | ON |
| P0420 | Catalyst system efficiency below threshold | ON |
| P0441 | EVAP system incorrect purge flow | ON |
| P0442 | EVAP system leak detected (small leak) | ON |
| P0443 | Purge solenoid valve circuit problem | ON |
| P0446 | EVAP system vent control circuit problem | ON |
| P0455 | EVAP system leak detected (large leak) | ON |
| P0456 | EVAP system leak detected (very small leak) | ON |
| P0461 | Fuel gauge sender unit circuit range/performance | ON |
| P0462 | Fuel gauge sender unit (main) circuit low input | ON |
| P0463 | Fuel gauge sender unit (main) circuit high input | ON |
| P0480 | Cooling fan No.1 control circuit problem | OFF |
| P0481 | Cooling fan No.2 control circuit problem | OFF |
| P0500 | VSS circuit problem | ON |
| P0505 | Idle air control system problem | OFF |
| P0506 | Idle air control system RPM lower than expected | ON |
| P0507 | Idle air control system RPM higher than expected | ON |
| P0562 | System voltage low (KAM) | ON |
| P0564 | Cruise control switch input circuit problem | OFF |
| P0571 | Brake switch input circuit problem | OFF |
| P0601 | PCM memory check sum error | ON |
| P0602 | PCM programming error | ON |
| P0604 | PCM random access memory error | ON |
| P0610 | PCM vehicle options error | ON |
| P0638 | Throttle actuator control circuit range/performance | ON |
| P0661 | SSV solenoid valve control circuit low | ON |
| P0662 | SSV solenoid valve control circuit high | ON |
| P0703 | Brake switch input circuit problem | ON |
| P0704 | CPP switch input circuit problem | ON |
| P0850 | Neutral switch input circuit problem | ON |
| P1260 | Immobilizer system problem | OFF |
| P1686 | Metering oil pump control circuit low flow side problem | ON |
| P1687 | Metering oil pump control circuit high flow side problem | ON |
| P1688 | Metering oil pump control circuit initial check problem | ON |
| P2004 | APV stuck open | ON |
| P2006 | APV motor control driver IC problem | ON |
| P2009 | APV motor control circuit low input | ON |
| P2010 | APV motor control circuit high input | ON |
| P2016 | APV position sensor circuit low input | ON |
| P2017 | APV position sensor circuit high input | ON |
| P2067 | Fuel gauge sender unit (sub) circuit low input | ON |
| P2068 | Fuel gauge sender unit (sub) circuit high input | ON |
| P2070 | SSV stuck open | ON |
| P2096 | Target A/F feedback system too lean | ON |
| P2097 | Target A/F feedback system too rich | ON |
| P2102 | Throttle actuator power supply line circuit low input | ON |
| P2103 | Throttle actuator power supply line circuit high input | ON |
| P2106 | Throttle actuator control system-forced limited power | ON |
| P2107 | Throttle actuator control module processor error | ON |
| P2108 | Throttle actuator control module performance error | ON |
| P2109 | TP sensor minimum stop range/performance problem | ON |
| P2112 | Throttle actuator control system range/performance problem | ON |
| P2119 | Throttle actuator control throttle body range/performance | ON |
| P2122 | APP sensor No.1 circuit low input | ON |
| P2123 | APP sensor No.1 circuit high input | ON |
| P2127 | APP sensor No.2 circuit low input | ON |
| P2128 | APP sensor No.2 circuit high input | ON |
| P2135 | TP sensor No.1/No.2 voltage correlation problem | ON |
| P2136 | TP sensor No.1/No.3 voltage correlation problem | ON |
| P2138 | APP sensor No.3/No.4 voltage correlation problem | ON |
| P2195 | Front HO2S signal stuck lean | ON |
| P2196 | Front HO2S signal stuck rich | ON |
| P2257 | AIR pump relay control circuit low | ON |
| P2258 | AIR pump relay control circuit high | ON |
| P2259 | AIR solenoid valve control circuit low | ON |
| P2260 | AIR solenoid valve control circuit high | ON |
| P2270 | Rear HO2S signal stuck lean | ON |
| P2271 | Rear HO2S signal stuck rich | ON |
| P2401 | EVAP system leak detection pump control circuit low | ON |
| P2402 | EVAP system leak detection pump control circuit high | ON |
| P2404 | EVAP system leak detection pump sense circuit range/performance | ON |
| P2405 | EVAP system leak detection pump sense circuit low | ON |
| P2407 | EVAP system leak detection pump sense circuit intermittent/erratic | ON |
| P2502 | Charging system voltage problem | OFF |
| P2503 | Charging system voltage low | OFF |
| P2504 | Charging system voltage high | OFF |
Flashing CEL
A flashing Check Engine light in any modern Mazda means that the ECU is detecting a misfire (standard OBD-II behavior). Period. There are no other conditions that will trigger a flashing CEL.
Misfires can be caused by numerous different possible failures, and are involved in nearly every common parts failure in the RX-8. They need to be addressed quickly however, as they can lead to additional cascading failures if ignored in addition to killing your fuel economy and power.
Start your diagnosis and troubleshooting here: Suffering Misfire? Start Here