What is a Code 0170, fuel trim malfunction?

For this code, you need to look at live data on the scanner. Add upstream O2 sensor data for bank 1 to the scanner display and start the engine. P0170 indicates bank one is out of range. Does bank one read higher or lower than normal? Normal is around 0.5 volts. If higher, you are too rich. If lower, you are too lean. If too rich, you may have a leaky injector. If lean, you may have a vacuum leak or dirty injectors.

P1174 - Fuel trim adaptive malfunction (Bank 1)
P1175 - Fuel trim adaptive malfunction (Bank 2)

P0170 Fuel Trim Malfunction (Bank 1) OBD-II Trouble Code Technical Description Article by Dale Toalston ASE Certified Technician Fuel Trim Malfunction (Bank 1) What does that mean? This code is one that surfaces with certain makes of automobiles more than others. In writing this article I've added Mercedes-Benz-specific info since it seems that M-B (and VW) are most prone to having this P0170 surface along with misfire codes or other fuel trim codes. P0170 means there was a malfunction in the computer's control of the air:fuel ratio. It also indicates that the fuel trims reached their limit of adding fuel while trying to compensate for a actual or perceived rich condition. When the fuel trims reach their rich correction limit, the PCM (Powertrain Control Module) sets a P0170, indicating a problem or malfunction in the fuel trims. It may also have a P0173 referring to the same malfunction but on bank two. Symptoms Symptoms of a P0170 DTC may include: MIL (Malfunction Indicator Lamp) Illumination Start and stall Poor fuel economy Black smoke at tailpipe Hesitation/misfire at idle or under load Causes Potential causes include a vacuum leak, unmetered air leaks Fuel saturated engine oil Leak in turbo air charge hoses (if equipped) Possibly bad O2 sensor (If Mercedes, may require adaptation with M-Benz compatible scan tool.) Oil contamination in MAF connector or O2 sensor connectors. Also check ignition coils, cam and crank sensors, and oil sensor for leakage contributing to oil intrusion in wiring harness. Defective MAF (Mass Air Flow) sensor (especially on Mercedez-Benz and other European autos. There are a lot of problems with aftermarket MAF sensors.) Defective fuel pressure regulator Leaking camshaft adjuster solenoids (Mercedes-Benz). NOTE: for some Mercedes-Benz models there is a service recall for a crankcase vent hose located under the intake manifold. It should be checked for leaks/cracking and also operation of check valve in the hose. The check valve should flow only one way. Possible Solutions It should be stated right off the bat that the most common problem associated with this code is the MAF sensor or air mass meter. This is especially the case with Mercedes-Benz and Volkswagen and other European cars. At time of writing, you don't normally see this code with American-made cars, and minimally with Asian, and, to be honest, I have no idea why. It appears to me that the PCM (powertrain control module) logic used by some European car manufacturers to set a P0170 (or P0173) fault code simply isn't used by American vehicle manufacturers. It is more common to see P0171, 0174, 0172, 0175 codes set with regard to fuel trim malfunctions on American cars. There is very little information on the setting conditions for a P0170, or P0173, but what information that is available almost seems to be a redundancy of the P0171,4,2 & 5 setting conditions. I'm sure there's a reason for it, but I can't get anyone to tell me what that is. The similarities between them may be why we don't see this code surface on domestic vehicles very often. It's simply unnecessary. So, simply put, if you have a P0170, your PCM noticed that the fuel trims reached their rich correction limit. Basically it's adding fuel to try to compensate for a lean condition, real or perceived. If you have this code and access to a scan tool, observe the MAF sensor reading in grams/sec. The reading will be different for different automobiles, so get a good spec. I'm going to stick with what would be normal for a Mercedes (1.8L), since they have the bulk of the trouble. Expect to see at idle 3.5-5 g/s (ideally). At 2500 RPMs with no load it should be between 9 and 12 g/s. On road test, at WOT (wide open throttle) it should be 90 g/s or well above. If it's not in specs, replace it. Be careful of Ebay MAFs. Often they don't work according to OE specifications. If the MAF checks out and there is no oil intrusion at the connector, check fuel pressure and ensure that there are no leaks at the regulator internally or externally. Check all vacuum hoses and confirm none are cracked, disconnected or missing. Make sure there are no vacuum leaks at the intake manifold gaskets or tears in the air supply hose. If the engine is turbo charged, be sure the hoses are in good condition and have no leaks. Leaking turbo pressure hoses could cause a rich condition. Inspect the condition of crankcase vent hose under intake manifold and operation of check valve in the hose. (In the "What are the causes?" section) If there doesn't appear to be any problems with the fuel pressure, MAF or vacuum hoses, then inspect the O2 sensor connectors for oil intrusion. A bad O2 sensor could cause a P0170, or P0173. Repair cause of oil leak and replace oil-fouled O2 sensor.

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code p0170 refers to two problems
fuel trim bank 1 --malfunction
heated oxygen sensor(HO2S) 3 bank1 --circuit malfunction
for the first error==causes-- intake leak --AIR system---fuel pressure /pump---injectors--EVAP canister purge valve---HO2S
for the second one ===causes=--wiring--HO2S---ECM
The explanation of fuel trim is long winded and you may get some typo errors but I think that you will get the idea
short and long term fuel trim refers to the strategy used to reduce exhaust emissions after a basic computation of injector period, using engine load as a major parameter
both front and rear oxygen sensors signals are used to fine tune the air/fuel mixture by increasing or decreasing the injection period =/- 25% above or below the basic level
any fault requiring a correction beyond this level will result in a fault code being logged ( in this case p0170)
the fuel trim will oscillate the injection period =/- 5% above or below the mean level level A
manufacturing and in-service tolerances of load sensors (MAP,MAF, VAF) and injectors in particular and faults such as intake leaks( vacuum hoses from vent controls and transmission) will affect the air/fuel mixture and cause the trim to compensate
an air intake leak for instance would increase the injection period increasing for example to 115-125%. this level will also oscillate +/- as before level B
this new short term fuel trim level will be stored in the ECM if it is established as a new basic mixture level
It will become a long term fuel trim correction and results in the correct mixture level immediately after starting, even when the HO2S has had sufficient time to heat up
Now having some idea of what trim is, you will see the necessity of repairing any problem sensors ,air leaks ,vacuum leaks
You will also probably understand the reason of why an engine after running short runs ( city driving) feels that it gets more power and better economy after 1/2 hour on the open highway
The ECM resets the trim to the new load power settings and that becomes the new trim

ode p0170 refers to fuel trim (FT) bank 1 malfunction==causes---intake leak--AIR system---fuel pressure/pump---injector/s--EVAP canister purge valve---HO2s
Code p0480 refers to engine coolant blower motor 1--circuit malfunction===causes---wiring---engine coolant blower motor---ECM

P0170 Fuel Trim (Bank 1)
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new version fgtech v53

DTC P2187: Fuel Trim System Lean at Idle

Fuel Trim Description
The Engine Control Module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during Open and Closed Loop. During Open Loop, the ECM determines fuel delivery based on sensor signals without Heated Oxygen Sensor (HO2S) input. During Closed Loop, the HO2S inputs are added and used by the ECM to calculate short and long term fuel trim fuel delivery adjustments. If the HO2S indicate a lean condition, fuel trim values will be above 0%. If the Heated Oxygen Sensors (HO2S) indicate a rich condition, fuel trim values will be below 0%. Short term fuel trim values change rapidly in response to the HO2S signals. Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7 : 1.

This code can only set when the engine control is in Closed Loop. The engine must be fully warmed up.

This must be diagnosed using a scan tool that can read engine data in order to determine the actual cause of the problem. It can be caused by the following things:

> Vacuum leaks
> Malfunctioning, dirty, or skewed Mass Airflow Sensor (MAF)
> Malfunctioning or skewed Manifold Absolute Pressure Sensor (MAP)
> Dirty or sticking injectors
> Malfunctioning or improperly programmed Powertrain Control Module (PCM)

The oxygen sensor is possibly bad on bank 1. Just a little advise, I work and produce these, and the after market is just as good if not better. It ends a signal to trim the gas back if the gas/air ratio isn't correct, same thing with if it needs more gas it will trim back the air ratio and more gas will be introduced.

fuel trim adaption additive bank 1 malfunction this means that the intake manifold gasket may be leaking or plug cap and the vacuum hose for the fuel pressure regulator hose maybe torn or missing check these look for leaks backside motor be black gunk all around them and check the hose

P0170 Fuel Trim Malfunction (Bank 1)