CLK430 CEL - Codes read P0170 & P0173 + blinking low fuel (once) - PeachParts Mercedes-Benz Forum

stim141 · #1 04-10-2012, 08:37 AM

First - car has a slight rough idle - has been that way for several weeks. Last week had the car in for a rear main seal replacement. Drove the car about 50 miles since. Yesterday - CEL came on. Codes were read by a auto store and they pulled P0170 and P0173. Hour later the fuel gauge low light blinked. Turned car off and restarted and it has reappeared.

Bought a can of MAF cleaner and blew out the filters and cleaned several times the MAF when it was out of the car. Waited for it to dry completely and reinstalled everything. Same symptoms but haven't driven it a few starts to attempt to clear the codes and haven't disconnected the battery.

First - is this the codes and symptoms for a bad MAF? What is the blinking fuel gauge? Is it possible that the shop may have damaged any of the O2 sensors during disassembly or knocked something else? What else should I consider with the two thown codes?

Any help would be appreciated.

porkface · #2 04-10-2012, 10:28 AM

3 things, always. vacuum leaks, low fuel pressure and dead mass meter. had 1 car that needed all 3 things corrected before it straightened out. look at the hoses to the amm and make sure nothing got knocked off during the seal job. otherwse, you need a smoke machine, a fuel pressure gauge you can watch while driving and an obd2 tool that lets you look at data while driving. the adaptation must be reset before and after and a battery disconnect won't do it. good luck, chuck.

duxthe1 · #3 04-10-2012, 01:54 PM

Blinking low fuel light indicates a leak in the fuel tank evaporative purge system. There is a "purge valve" in the engine bay that feeds the vapor to the engine, a canister shut-off valve in the rear, as well as the integrity of the tank, lines, and cap that have to all be good to prevent it. It will definitely set the C/E light if there is an evaporative leak.

RichardM98 · #4 04-10-2012, 05:25 PM

Codes P0170 and P0173 while not specific MAF codes are usually what pops up when the MAF goes south. Since cleaning didn't help be sure to get the CORRECT Bosch insert from a reputable supplier like this site.

Unrelated, the low fuel light is a signal of a leak. In order, check the fuel cap, fuel cap gasket and then the leak possibilities all ready mentioned.

stim141 · #5 04-11-2012, 09:04 AM

Thanks for the replies. Going to check it out tonight. Idle is still rough even with the cleaning - so I'm assuming the MAF is bad. Will start to check out the fuel system as well. For the money the insert is def the way to go versus spending another 100+ for basically what amounts to a piece of plastic.

duxthe1 · #6 04-11-2012, 01:36 PM

We had such high failure rates with the insert the we stopped selling them at our shop!

fdm_alex · #7 04-12-2012, 01:17 AM

Hey hold on there! If you have rough running and also those codes, make sure your gas cap is on tight! I know it sounds stupid, but a loose gas cap or one with a leaking seal will cause both of those problems, sometimes even enough to set a misfire code. Would hate to have you spend MAF money for no reason. I've seen it before...