SL/R129: Check Engine Light
01-17-2015, 05:23 PM
#1
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1998 SL 500
Check Engine Light
Hi,
I would like to know if any owner knows what the Diagnosis code P0170 mean ( Bank 1 ) on a 1998 SL 500? I had a mechanic buddy of mine plug the obd II to read the diagnosis code and is not sure what it is. Thanks in advance.
I would like to know if any owner knows what the Diagnosis code P0170 mean ( Bank 1 ) on a 1998 SL 500? I had a mechanic buddy of mine plug the obd II to read the diagnosis code and is not sure what it is. Thanks in advance.
01-17-2015, 09:07 PM
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1998 SL500
It is "Fuel trim malfunction bank 1", was that the only code?
Fuel trim is how the ECU controls the air/fuel ratio when running in closed loop mode, I.e. when it is using the O2 sensor's reporting of a lean or rich mix to adjust the injector pulse width--and therefore the amount of fuel injected--closed loop operation only occurs at lower loads (below 60%) and throttle settings, at higher loads the ECU enters open loop mode where fueling is determined by lookup tables (using load, engine speed, etc.) sometimes modified by long term fuel trims adaptively learned averages of the short term values calculated in closed loop mode.
It could be a vacuum leak, PCV problem, bad O2 sensor, bad MAF...
Fuel trim is how the ECU controls the air/fuel ratio when running in closed loop mode, I.e. when it is using the O2 sensor's reporting of a lean or rich mix to adjust the injector pulse width--and therefore the amount of fuel injected--closed loop operation only occurs at lower loads (below 60%) and throttle settings, at higher loads the ECU enters open loop mode where fueling is determined by lookup tables (using load, engine speed, etc.) sometimes modified by long term fuel trims adaptively learned averages of the short term values calculated in closed loop mode.
It could be a vacuum leak, PCV problem, bad O2 sensor, bad MAF...
02-26-2015, 08:01 PM
#3
Former Vendor of MBWorld
I would start from the bottom and work up, clean the MAF with some MAF cleaner. Unplug your battery negative terminal for 30 minutes and plug it back in. That fixed mine. If it's something a vacuum leak, unplug a vacuum hose and look up "diagnose vacuum leak with cigar." good luck.
