"Depollution System Faulty" Error Code

What your Service Centers normally don't tell you!

I never send my cars to any workshop when "Depollution System Faulty" pops up. I'm sharing what u oughta know... the reasons why, what parts to replace and how much u have to pay for.

Frm oneDIY (formerly known as uncleDIY) experience... there are at least one out of three main culprits for the error code. Each symptom is unique...

1. The engine runs normally or a little "not-so-smooth" (not jerky) at idling speeds and can be driven slowly but jerky when the accelerator pedal is pressed harder.

Reason: Faulty/dirty spark plug. Cost of part replacement is less than or around RM50 for a platinum or iridium spark plug.

2*. The engine runs uneven and jerky/erratic at idling and can only be driven at extremely slow speeds or not at all.

Reason: Faulty ignition coil. Cost of part replacement is around RM200 for individual ignition coil pack. Some cars come with integrated coil pack (4-in-1) costs around RM500.

3.The error code displayed but there is no noticeable effect on the engine and the car can be driven normally.

Reason: Faulty Oxygen Sensor. Cost of part including labour can be more than RM1k. I bought @US$132.98 frm eBay 2 yrs ago.

*Note: "ol' school" type of engine, using a single ignition coil together with a distributor may not applied this symptom.

WARNING! Imitation Spark Plugs

How to Identify Imitation Spark Plugs? [from NGK website]

click on the image to enlarge

When I checked the factory fitted NGK platinum spark plugs on my Peugeot 308 I got these laser-print "four-digit number" on the bi-hex... "H7Z8." as shown in the picture below.

and also some numbers are stamped on the spark plug body [serial number or something?].


Genuine NGK electrodes [platinum tip and disc] at 40,000km!...

...the tip and disc are still shiny and intact - probably counterfeit tip and disc would have already vaporized at 40,000km.

What about "Laser Iridium" spark plugs which some of you and I bought on-line?





The welding around the electrode looks a little weird to me....

There is also no "four-digit number" stamped/printed on the bi-hex.
I decided not to use these "questionable" spark plugs. Investigation with NGK is in progress.

UPDATE: Received an email from Andrew Hauenstein, Technical & Training Specialist, NGK Spark Plugs (USA), Inc - Friday July 1st 2011

"The build date (four-digit code) should be marked vertically on the BI-Hex. Yes our Laser plugs are laser welded.... ",

So IMHO, NGK spark plugs without the "four-digit" code marking on the bi-hex could be fake or failed QC.

Iridium Spark Plugs

FAQ: Any Improvement in Performance for using Iridium Spark Plug?
I think they add nothing more to performance than new and clean standard spark plugs. Experts also say little to none as far as power gains.
They might last longer since Iridium alloy spark plugs take longer to wear out.

What is Iridium in the First Place?
Iridium is a very hard and brittle metal [in the same family as the Platinum], is one of the rarest elements ever found on earth. It is the heaviest metal known to mankind beside Osmium and is the most corrosion-resistant metal even at 2000 °C. Annual production and consumption only three tonnes. As expensive as Gold but Iridium alloys [with Osmium and Ruthenium] can be up to five times more expensive!

Some scientists suggest that Iridium [first discovered in 1803] came down to the earth with the asteroids because it is found in meteorite fragments much higher than its average abundance in the Earth's crust...

Why Iridium Spark Plug?
Iridium spark plugs wear out much slower due to its super strength against corrosion/oxidation/wear&tear at extreme temperatures and pressures in hell-like environment of the combustion chambers.

Nevertheless, it is a common misconception that Iridium spark plugs give more horse power and better fuel consumption. The truth is if the conventional spark plug is new and in good condition, we still can get best fuel consumption and maximum performance from the engine.

It doesn't matter which kind of spark plug we use as long as it is within the specifications. If freshly installed, there is no difference at all. But after more than 20,000km, the cheap or standard plugs give a little bit more fuel consumption and reduce power while the Iridium plugs are still as good as new....

... up to 200,000km for iridium spark plug with platinum ground-electrode[?]

What about "Multi-electrode" spark plugs?
This type of spark plugs produce only one spark on the smallest gap available. The wear is divided over multiple gaps so it stays "fresher" for a longer time. For instance, for a 4-electrode spark plug, it takes about 4 times longer for those to show the same wear as standard plugs.

This means that we can keep them 4 times longer or replace them in the normal interval and have a better spark in average. Again, it is another myth saying that multi-electrode spark plug gives higher performance.I use 4-electrode plugs for a D-segment car and keep them twice as long. This generates the same costs for spare plugs but gives me a slightly better spark where standard ones would be seriously worn already.

The Truths?
Iridium and multi-electrode spark plug do not produce higher horse-power and give lower fuel consumption so to speak. They just maintain top performance longer than the conventional/standard spark plus. That's all...

Conclusion?
As an analogy, it does not matter whether you use 18k-Gold Zippo Lighter or Mancis Cap Lada to light-up an Altadis’ Behike Cigar!