LPG Discussion Forum

Hi all,
New to forum. need help with my zafira.

Problem : EML and TC on

Taken to dealer for diagnostics - ripped off £58+ £ 97 codes C0256,P0202 &P0134.
Suggested further diagnostics -£100 more may be ECU fault cost £500 plus
Very unhappy with the treatment!
While waiting for repairs had few violent stalls and misfire.
Car running better in LPG than petrol. With help of google and mechanic friend purchased op-com did diagnostics and have replaced spark plugs,air flow meter and coil pack.
Car running better! LPG better than petrol but still shows C0256 and P0202.

Running out of options!
Please help!
Thanks.

taken from http://www.obd-codes.com/p0202

P0202 - Cylinder 2 Injector Circuit Malfunction

Cylinder 2 Injector Circuit Malfunction

What does that mean?

P0202 means that the PCM detected a fault in the injector or the wiring to the injector. It monitors the injector and when the injector is activated, the PCM expects to see the voltage pulled "low" or close to zero. When the injector is switched off, the PCM expects to see a voltage that is close to battery voltage or "high". If it doesn't see the expected voltage the PCM will set this code. The PCM also monitors resitance in the circuit. If the resistance is excessively low or high it will set this code.

Potential Symptoms

The symptoms for this code will likely be a misfire and a rough running engine. Poor acceleration. The MIL will also be illuminated.

Causes

The causes of a P0202 engine light code could be any of the following:

Bad injector. This is usually the cause of this code but doesn't rule out the possibility of one of the other causes
Open in the wiring to the injector
Short in the wiring to the injector
Bad PCM


C0256- Engine torque reduction malfunction

thanks.

How do I access the injector & circuit to check them?

I'd be suspicious of wonky connections in the LPG emulator unit, that the petrol injector signals are routed through.

I assume the codes are generated when running on petrol.

Start by connecting the petrol injectors directly back to the pertol ECU. Not thought the LPG ECU.

To test your injectors simply, disconnect the wiring plug off all 4, test the resistance of the injectors with a meter. All 4 should be the same +-0.2 Ohms.
If one is much lower there is a short in the coil of the injector. Means it may not open fully if at all, too high will also cause the same problem.
If their all the same, reconnect injectors 2,3,4. Turn on the engine, it will run very rough. Test the voltage from the petrol ECU with the meter.
Then reconnect injector 1 and disconnect 2, repeat till all 4 are done, you should get the same voltage pulse from all 4.
Do no check the wiring on resistance settings! This will send a voltage down the wiring to the ECU. If you want to check for wiring short, unplug the ECU and test the ECU side to the injector connector side.
Its best to have your cars wiring diagram to decide on the best testing solution.

Alternatively, if you have the software and programming lead for the LPG
ECU and it connects to the injector loom, then you can see from software display the injectors timings, this will tell you if the petrol ECU is sending correct signals. A short would show up there.

Someone may correct me here but that is what I would do to find the fault.

lpgnewbbie wrote:Start by connecting the petrol injectors directly back to the pertol ECU. Not thought the LPG ECU.

It's a factory fit so the loom doesn't allow for bypassing. Remember a factory fit is designed to have 2 sets of injectors so has a loom that includes connectors for both sets.

Thanks for the replies.
I'm novice and confused now with the suggestions.
Please give step by step instruction to access and check injectors. It's a factory fit LPG system by Millbrooks and is
Necam-Koltec system I think!
I have op-com (e-bay) and can provide some data of the system.

Ram